Atypical Multinail Median Canaliform Dystrophy of Heller with Toenail Involvement: A Case Report

Atypical Multinail Median Canaliform Dystrophy of Heller with Toenail Involvement: A Case Report | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Atypical Multinail Median Canaliform Dystrophy of Heller with Toenail Involvement: A Case Report Jamiel Reyes This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8971252/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Purpose Median canaliform dystrophy of Heller (MCDH) is a rare nail matrix disorder typically affecting one or both thumbnails. Multinail involvement, including toenails, is rarely reported. We describe a case with atypical multi-digit involvement to broaden the recognized clinical spectrum. Methods A 29-year-old male underwent dermatologic evaluation for chronic, asymptomatic nail deformities of both thumbnails and the left great toenail. Diagnosis was made clinically based on characteristic morphology after systematically excluding onychomycosis, habit-tic deformity, and inflammatory nail disorders. Results Examination revealed central longitudinal canals with symmetric oblique lateral ridging forming a fir-tree pattern. Periungual tissues were normal, and there was no history of trauma, manipulation, systemic disease, or medication exposure. A clinical diagnosis of MCDH was established. The patient was managed conservatively with reassurance and advice to avoid microtrauma. At six-month follow-up, nail changes were stable and asymptomatic; the patient reported understanding the benign nature of the condition. Conclusions This case demonstrates an uncommon idiopathic presentation of MCDH involving bilateral thumbnails and a toenail. Awareness of such atypical presentations can prevent misdiagnosis, unnecessary testing, and inappropriate interventions. Medial canaliform dystrophy Nail matrix disorder Nail dystrophy Fir-tree nail deformity Multinail involvement. Figures Figure 1 Figure 2 Figure 3 Introduction Median canaliform dystrophy of Heller (MCDH), also known as nevus striatus unguis, is a rare benign disorder of the nail matrix first described by Heller in 1928. It is characterized by a central longitudinal canal originating at the proximal nail fold and extending distally, often accompanied by oblique lateral fissures forming a fir-tree or inverted Christmas tree pattern (Satish et al. 2025 ). MCDH typically affects one or both thumbnails, though involvement of additional fingernails or toenails is infrequently reported (Pauliņa and Balcere 2023 ; Wang et al. 2020 ). Its pathogenesis remains incompletely understood but is thought to involve transient focal disruption of keratinization within the proximal nail matrix. Reported associations include repetitive trauma, occupational microtrauma, psychological stress, and retinoid therapy (Raizada et al. 2020 ; Pauliņa and Balcere 2023 ), although many cases are idiopathic. Because of its rarity and morphological similarity to other nail disorders, MCDH is often misdiagnosed, potentially resulting in unnecessary antifungal therapy or invasive diagnostic procedures. Here, we report a case of bilateral thumbnail and concurrent toenail involvement in a young adult male, highlighting an unusual presentation and expanding the known clinical spectrum of MCDH. Recognizing such atypical presentations is clinically important to prevent misdiagnosis and unwarranted interventions. This case report was prepared in accordance with the CARE guidelines for case reports. The completed CARE checklist is provided as Supplementary Material. Case Presentation Patient Information A 29-year-old male of white ethnicity working as a healthcare professional presented with several-years history of asymptomatic nail changes. He reported no pain, pruritus, discharge, fragility, or functional impairment. There was no history of trauma, repetitive nail manipulation, systemic illness, or medication use. Family history was noncontributory. Clinical Findings Examination revealed longitudinal midline canals extending from the proximal nail fold to the distal nail edge of both thumbnails, with symmetrical lateral ridging producing a characteristic fir-tree pattern (Figs. 1 and 2 ). The left great toenail showed similar but less pronounced changes (Fig. 3 ). Nail plate thickness was preserved, and there was no chromonychia, subungual hyperkeratosis, or onycholysis. No other fingernails or toenails were affected. Timeline A timeline of the clinical course is summarized in Table 1 . Table 1 Timeline of Clinical Events a Event Timeline Onset of nail changes ~ 5 years prior to presentation Progressive involvement Limited to thumbnails and left great toenail Clinical evaluation Initial dermatology visit Follow-up 6 months post initial visit, nails stable ᵃ Timeline reconstructed from patient history and clinical evaluation. Diagnostic Assessment A clinical diagnosis of Median Canaliform Dystrophy of Heller (MCDH) was made. Differential diagnoses were systematically excluded as summarized in Table 2 . The absence of chromonychia, subungual hyperkeratosis, onycholysis, or distal involvement made onychomycosis unlikely; therefore, mycologic testing was not pursued. Table 2 Differential Diagnosis and Rationale for Exclusion a,b Differential Diagnosis Features Present Rationale for Exclusion Onychomycosis None (no discoloration, thickening, subungual debris) Clinical features absent; mycologic testing not indicated Habit-tic deformity None (no cuticular damage, no transverse ridges) No history of habitual manipulation or proximal nail fold trauma Nail lichen planus None (no pterygium, no progressive thinning) Absence of periungual inflammation or discoloration Traumatic median nail split None (no history of trauma) Clinical pattern not consistent ᵃ Diagnosis was based on characteristic clinical morphology and systematic exclusion of common longitudinal nail dystrophies. ᵇ Mycologic testing was not performed due to the absence of clinical features suggestive of onychomycosis. Therapeutic Intervention Conservative management was recommended: avoidance of potential microtrauma, no pharmacologic treatment prescribed, and patient reassurance regarding the benign nature of the condition. Follow-Up and Outcomes At 6-month follow-up, the nail changes remained stable, asymptomatic, and the patient reported understanding the condition and comfort with conservative management. Patient Perspective The patient expressed reassurance after understanding the benign nature of the condition. Discussion Median canaliform dystrophy of Heller (MCDH), also known as nevus striatus unguis, is a rare benign nail matrix disorder characterized by a central longitudinal canal with lateral fissures forming the classic fir-tree appearance (Satish et al. 2025 ). Despite being described nearly a century ago, MCDH remains underrecognized, often leading to misdiagnosis and unnecessary interventions (Pauliņa and Balcere 2023 ; Wang et al. 2020 ). Most reports derive from isolated case studies or small series, so its true incidence is not well established. The pathogenesis is incompletely understood but likely involves transient or localized dysfunction of the proximal nail matrix during keratinization, resulting in the formation of a central groove with symmetric lateral ridges (Richert et al. 2015 ). Proposed precipitating factors include repetitive or occupational trauma (Raizada et al. 2020 ), habitual nail manipulation, psychological stress (Pauliņa and Balcere 2023 ; Wang et al. 2020 ; Satish et al. 2025 ), familial predisposition (Sweeney et al. 2005 ), and medication exposure such as systemic retinoids (Pathania 2016 ). However, many cases remain idiopathic, as in the present patient, suggesting that intrinsic matrix vulnerability may play a role. While MCDH most commonly affects one or both thumbnails, involvement of additional fingernails or toenails is rare (Pauliņa and Balcere 2023 ; Wang et al. 2020 ; Tosti et al. 2006 ). The current case demonstrates concurrent bilateral thumbnail and left great toenail involvement in an adult patient without identifiable triggers, a presentation rarely described in the literature. Previous reports of multinail disease typically involve pediatric patients, retinoid-associated cases, or those with precipitating factors (Li and Shou 2025 ; Saddik et al. 2023 ). The chronic, stable, idiopathic presentation in this adult patient underscores the heterogeneity of MCDH manifestations. Differential diagnosis includes longitudinal nail dystrophies such as onychomycosis, nail psoriasis, nail lichen planus, habit-tic deformity, and traumatic median splits (Elewski 1998 ; Tosti et al. 2006 ; Alessandrini et al. 2017 ; Inthasot et al. 2022 ; Rachadi and Chiheb 2024 ). Accurate identification of the central canal with symmetric lateral ridging is essential to avoid unnecessary antifungal therapy or invasive procedures. Onychomycosis is usually accompanied by chromonychia, subungual debris, and nail thickening (Elewski 1998 ). Habit-tic deformity presents with transverse ridges and proximal nail fold damage (Alessandrini et al. 2017 ). Nail lichen planus exhibits pterygium formation, progressive thinning, and periungual inflammation (Tosti et al. 2006 ), whereas traumatic splits correlate with localized injury history (Inthasot et al. 2022 ). Dermoscopy can serve as a noninvasive diagnostic adjunct, revealing a central groove with regularly arranged lateral fissures, parallel whitish lines, and distal nail plate splitting (Satish et al. 2025 ; Pauliņa and Balcere 2023 ; Alessandrini et al. 2017 ). Dermoscopic evaluation may help distinguish MCDH from infectious or inflammatory nail disorders, though it was not performed in this patient. Management lacks standardized guidelines. Conservative measures, including patient education and avoidance of microtrauma or habitual manipulation, remain first-line (Satish et al. 2025 ). Spontaneous improvement has been reported, though some cases remain stable for years. Anecdotal treatments include topical tacrolimus (Kim et al. 2010 ), intralesional corticosteroids, and Nd:YAG laser therapy (Choi et al. 2017 ). In this case, conservative management with reassurance was appropriate and effective. This report highlights important clinical points: MCDH can involve multiple nails including toenails even without clear triggers, clinical assessment can establish diagnosis without unnecessary tests, and recognition of atypical presentations prevents misdiagnosis and overtreatment. Limitations include the absence of dermoscopic examination and mycologic testing, which could provide additional diagnostic confirmation in atypical or progressive cases. Future studies should clarify pathophysiology, risk factors, and optimal management strategies. Overall, this case further expands the clinical spectrum of MCDH, emphasizing that idiopathic multinail involvement is possible and reinforcing the value of accurate diagnosis and patient counseling (Li and Shou 2025 ; Saddik et al. 2023 ). Conclusion Median canaliform dystrophy of Heller (MCDH) is a rare, benign nail matrix disorder that may occasionally involve multiple nails. This case demonstrates an idiopathic presentation with bilateral thumbnail and left great toenail involvement in a young adult male without identifiable risk factors. Clinical recognition of atypical presentations is essential to prevent misdiagnosis, avoid unnecessary diagnostic testing, and reduce inappropriate interventions. Conservative management with patient education and reassurance remains the mainstay of care for asymptomatic cases. Abbreviations MCDH Median Canaliform Dystrophy of Heller Declarations Competing Interests The author declares no competing interests. Ethics Approval Not applicable. Consent to Participate Written informed consent was obtained from the patient for publication of this case report and accompanying images. Reporting Guidelines This report was prepared in accordance with the CARE guidelines. Author Contributions Statement J.R. conceived the study, collected and interpreted the clinical data, prepared all figures and tables, and wrote and revised the manuscript. J.R. approved the final version for submission and takes responsibility for all aspects of the work. Funding No funding was received. Author Contribution J.R. conceived the study, collected and interpreted the clinical data, prepared all figures and tables, and wrote and revised the manuscript. J.R. approved the final version for submission and takes responsibility for all aspects of the work. Acknowledgements The author thanks the patient for consent and cooperation Data Availability All relevant data are included within the article. References Alessandrini A, Starace M, Piraccini BM. Dermoscopy in the Evaluation of Nail Disorders. Skin Appendage Disord. 2017;3:70–82. https://doi.org/10.1159/000458728 . Choi J-Y, Seo H-M, Kim W-S. Median canaliform nail dystrophy treated with a 1064-nm quasi-long pulsed Nd:YAG laser. J Cosmet Laser Ther. 2017;17:225–6. https://doi.org/10.1080/14764172.2017.1279330 . Elewski BE. Onychomycosis: pathogenesis, diagnosis, and management. Clin Microbiol Rev. 1998;11:415–29. https://doi.org/10.1128/cmr.11.3.415 . Inthasot S, André J, Richert B. Causes of longitudinal nail splitting: a retrospective 56-case series with clinical pathological correlation. J Eur Acad Dermatol Venereol. 2022;36:744–53. https://doi.org/10.1111/jdv.17967 . Kim BY, Jin SP, Won C-H, Cho S. Treatment of median canaliform nail dystrophy with topical 0.1% tacrolimus ointment. J Dermatol. 2010;37:573–4. https://doi.org/10.1111/j.1346-8138.2009.00769.x . Li S-Q, Shou Y. Median canaliform dystrophy of Heller. QJM. 2025;118:925. https://doi.org/10.1093/qjmed/hcaf133 . Litaiem N, Mnif E, Zeglaoui F. Dermoscopy of Onychomycosis: A Systematic Review. Dermatol Pract Concept. 2023;13:e2023072. https://doi.org/10.5826/dpc.1301a72 . Pauliņa LA, Balcere A. Median Nail Canaliform Dystrophy in Association with Retinoid Therapy. Dermatol Pract Concept. 2023;13:2023184. https://doi.org/10.5826/dpc.1303a184 . Pathania V. Median Canaliform Dystrophy of Heller occurring on thumb and great toe nails. Med J Armed Forces India. 2016;72:178–9. https://doi.org/10.1016/j.mjafi.2015.06.020 . Rachadi H, Chiheb S. Dermoscopic features of nail psoriasis: a systematic review. Int J Dermatol. 2024;63:1013–9. https://doi.org/10.1111/ijd.17138 . Raizada A, Panda M, Behera D, Raj C. Stress associated median canaliform dystrophy of Heller; more prominent on dominant thumb. Our Dermatol Online. 2020;11:44–6. https://doi.org/10.7241/ourd.20201.10 . Richert B, Caucanas M, André J. Diagnosis using nail matrix. Dermatol Clin. 2015;33:243–55. https://doi.org/10.1016/j.det.2014.12.005 . Saddik A, El Fatoiki FZ, Skali H, et al. Bilateral median canaliform dystrophy of Heller of both toenails in a child. Int J Clin Med Case Rep. 2023. https://doi.org/10.46998/IJCMCR.2023.23.000573 . Satish J, Sanjana J, Gawali S, et al. Dermoscopy of Median Canaliform Dystrophy: A Rare Entity. Clin Dermatol Rev. 2025;9:104–5. https://doi.org/10.4103/cdr.cdr_75_24 . Sweeney SA, Cohen PR, Schulze KE, Nelson BR. Familial median canaliform nail dystrophy. Cutis. 2005;75:161–5. Tosti A, Piraccini BM, Iorizzo M. Nail lichen planus and other inflammatory nail disorders. Dermatol Clin. 2006;24:341–7. https://doi.org/10.1016/j.det.2006.03.007 . Wang C, Lee S, Howard A, Foley P. Coexisting median canaliform nail dystrophy and habit-tic deformity in a patient with atopic dermatitis. Australas J Dermatol. 2020;61:100–1. https://doi.org/10.1111/ajd.13084 . Additional Declarations No competing interests reported. Supplementary Files CAREchecklist.pdf Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 03 Apr, 2026 Reviews received at journal 02 Apr, 2026 Reviews received at journal 28 Mar, 2026 Reviewers agreed at journal 23 Mar, 2026 Reviewers agreed at journal 20 Mar, 2026 Reviewers agreed at journal 20 Mar, 2026 Reviewers invited by journal 20 Mar, 2026 Editor assigned by journal 03 Mar, 2026 Submission checks completed at journal 03 Mar, 2026 First submitted to journal 25 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8971252","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":610977709,"identity":"ed49940a-8ac6-422a-9124-0e92b7e1e461","order_by":0,"name":"Jamiel Reyes","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEElEQVRIiWNgGAWjYBACxgYGhgMMBRYMbFABORBx4AFBLQYScC3GYC0JBO0CaoGBxAYQiU8Lc/vpxAMfDCQS+/jPPnzMU1GXPj/s8EOgLXZyug04HNaTu+HgDKCWNol0Y2OeM4dzN95OMwBqSTY2O4DLL7kbDvOAtbCxSfO2HcjdODsBpOVA4jZcWvrfbjj8B6SF/xj7b95/demGs9M/4NcyA2gLA0gLQxobM28Dc4K8dA4BW2a83XCwx0DCuE0ijVlyzrHDhhukcwoOJBjg9othf+7mDz8qbGTn9x9j/PCmpk5efnb65g8fKuzkcGppQOIw8QAJA7BKA+zKQUAexZU/QCIN2FWOglEwCkbByAUA37Fjem7xZCoAAAAASUVORK5CYII=","orcid":"","institution":"Universidad de Ciencias Médicas de Holguín","correspondingAuthor":true,"prefix":"","firstName":"Jamiel","middleName":"","lastName":"Reyes","suffix":""}],"badges":[],"createdAt":"2026-02-25 21:09:47","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8971252/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8971252/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105566309,"identity":"849de0fb-92b7-4cc7-9613-fd58da9d016d","added_by":"auto","created_at":"2026-03-27 12:56:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":15281773,"visible":true,"origin":"","legend":"\u003cp\u003eRight thumbnail demonstrating central longitudinal canal with symmetric oblique lateral ridging, producing characteristic fir-tree appearance consistent with MCDH.\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-8971252/v1/0db3f95d91c31d2d433f00a9.png"},{"id":105433130,"identity":"2b8d30b9-4f24-4f3f-a2e3-b04b2f45acf4","added_by":"auto","created_at":"2026-03-26 02:58:06","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":17505284,"visible":true,"origin":"","legend":"\u003cp\u003eLeft thumbnail with more prominent longitudinal dystrophic changes and fir-tree pattern.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-8971252/v1/bee52acad6d8528aa7881b89.png"},{"id":105433128,"identity":"94590840-6b90-4e54-b1b4-d132b144462a","added_by":"auto","created_at":"2026-03-26 02:58:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":19678603,"visible":true,"origin":"","legend":"\u003cp\u003eMild longitudinal dystrophic changes involving the left great toenail.\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-8971252/v1/6daa3e8acdc3e65c42ede446.png"},{"id":105570297,"identity":"6fc0c9eb-c72a-47e8-8323-acfaef209170","added_by":"auto","created_at":"2026-03-27 13:15:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":46451793,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8971252/v1/fbf5e41d-bb8e-455f-bef9-5bce728cf544.pdf"},{"id":105433127,"identity":"4b2a832f-ec95-49bd-adca-281fb0e0e286","added_by":"auto","created_at":"2026-03-26 02:58:04","extension":"pdf","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":1238222,"visible":true,"origin":"","legend":"","description":"","filename":"CAREchecklist.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8971252/v1/692cec975c949ae03c2f70b6.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Atypical Multinail Median Canaliform Dystrophy of Heller with Toenail Involvement: A Case Report","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMedian canaliform dystrophy of Heller (MCDH), also known as nevus striatus unguis, is a rare benign disorder of the nail matrix first described by Heller in 1928. It is characterized by a central longitudinal canal originating at the proximal nail fold and extending distally, often accompanied by oblique lateral fissures forming a fir-tree or inverted Christmas tree pattern (Satish et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eMCDH typically affects one or both thumbnails, though involvement of additional fingernails or toenails is infrequently reported (Pauliņa and Balcere \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Its pathogenesis remains incompletely understood but is thought to involve transient focal disruption of keratinization within the proximal nail matrix. Reported associations include repetitive trauma, occupational microtrauma, psychological stress, and retinoid therapy (Raizada et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Pauliņa and Balcere \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), although many cases are idiopathic.\u003c/p\u003e \u003cp\u003eBecause of its rarity and morphological similarity to other nail disorders, MCDH is often misdiagnosed, potentially resulting in unnecessary antifungal therapy or invasive diagnostic procedures. Here, we report a case of bilateral thumbnail and concurrent toenail involvement in a young adult male, highlighting an unusual presentation and expanding the known clinical spectrum of MCDH. Recognizing such atypical presentations is clinically important to prevent misdiagnosis and unwarranted interventions.\u003c/p\u003e \u003cp\u003e This case report was prepared in accordance with the CARE guidelines for case reports. The completed CARE checklist is provided as Supplementary Material.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatient Information\u003c/h2\u003e \u003cp\u003eA 29-year-old male of white ethnicity working as a healthcare professional presented with several-years history of asymptomatic nail changes. He reported no pain, pruritus, discharge, fragility, or functional impairment. There was no history of trauma, repetitive nail manipulation, systemic illness, or medication use. Family history was noncontributory.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eClinical Findings\u003c/h3\u003e\n\u003cp\u003eExamination revealed longitudinal midline canals extending from the proximal nail fold to the distal nail edge of both thumbnails, with symmetrical lateral ridging producing a characteristic fir-tree pattern (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The left great toenail showed similar but less pronounced changes (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Nail plate thickness was preserved, and there was no chromonychia, subungual hyperkeratosis, or onycholysis. No other fingernails or toenails were affected.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eTimeline\u003c/h3\u003e\n\u003cp\u003eA timeline of the clinical course is summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTimeline of Clinical Events\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEvent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTimeline\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOnset of nail changes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e~\u0026thinsp;5 years prior to presentation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProgressive involvement\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLimited to thumbnails and left great toenail\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eClinical evaluation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial dermatology visit\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFollow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 months post initial visit, nails stable\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eᵃ Timeline reconstructed from patient history and clinical evaluation.\u003c/p\u003e\n\u003ch3\u003eDiagnostic Assessment\u003c/h3\u003e\n\u003cp\u003eA clinical diagnosis of Median Canaliform Dystrophy of Heller (MCDH) was made. Differential diagnoses were systematically excluded as summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The absence of chromonychia, subungual hyperkeratosis, onycholysis, or distal involvement made onychomycosis unlikely; therefore, mycologic testing was not pursued.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDifferential Diagnosis and Rationale for Exclusion\u003csup\u003ea,b\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDifferential Diagnosis\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFeatures Present\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRationale for Exclusion\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOnychomycosis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNone (no discoloration, thickening, subungual debris)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eClinical features absent; mycologic testing not indicated\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHabit-tic deformity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNone (no cuticular damage, no transverse ridges)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo history of habitual manipulation or proximal nail fold trauma\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNail lichen planus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNone (no pterygium, no progressive thinning)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAbsence of periungual inflammation or discoloration\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTraumatic median nail split\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNone (no history of trauma)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eClinical pattern not consistent\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eᵃ Diagnosis was based on characteristic clinical morphology and systematic exclusion of common longitudinal nail dystrophies.\u003c/p\u003e \u003cp\u003eᵇ Mycologic testing was not performed due to the absence of clinical features suggestive of onychomycosis.\u003c/p\u003e\n\u003ch3\u003eTherapeutic Intervention\u003c/h3\u003e\n\u003cp\u003eConservative management was recommended: avoidance of potential microtrauma, no pharmacologic treatment prescribed, and patient reassurance regarding the benign nature of the condition.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eFollow-Up and Outcomes\u003c/h2\u003e \u003cp\u003eAt 6-month follow-up, the nail changes remained stable, asymptomatic, and the patient reported understanding the condition and comfort with conservative management.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePatient Perspective\u003c/h3\u003e\n\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe patient expressed reassurance after understanding the benign nature of the condition.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eMedian canaliform dystrophy of Heller (MCDH), also known as nevus striatus unguis, is a rare benign nail matrix disorder characterized by a central longitudinal canal with lateral fissures forming the classic fir-tree appearance (Satish et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Despite being described nearly a century ago, MCDH remains underrecognized, often leading to misdiagnosis and unnecessary interventions (Pauliņa and Balcere \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Most reports derive from isolated case studies or small series, so its true incidence is not well established.\u003c/p\u003e \u003cp\u003eThe pathogenesis is incompletely understood but likely involves transient or localized dysfunction of the proximal nail matrix during keratinization, resulting in the formation of a central groove with symmetric lateral ridges (Richert et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Proposed precipitating factors include repetitive or occupational trauma (Raizada et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), habitual nail manipulation, psychological stress (Pauliņa and Balcere \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Satish et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), familial predisposition (Sweeney et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2005\u003c/span\u003e), and medication exposure such as systemic retinoids (Pathania \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). However, many cases remain idiopathic, as in the present patient, suggesting that intrinsic matrix vulnerability may play a role.\u003c/p\u003e \u003cp\u003eWhile MCDH most commonly affects one or both thumbnails, involvement of additional fingernails or toenails is rare (Pauliņa and Balcere \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Tosti et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). The current case demonstrates concurrent bilateral thumbnail and left great toenail involvement in an adult patient without identifiable triggers, a presentation rarely described in the literature. Previous reports of multinail disease typically involve pediatric patients, retinoid-associated cases, or those with precipitating factors (Li and Shou \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Saddik et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The chronic, stable, idiopathic presentation in this adult patient underscores the heterogeneity of MCDH manifestations.\u003c/p\u003e \u003cp\u003eDifferential diagnosis includes longitudinal nail dystrophies such as onychomycosis, nail psoriasis, nail lichen planus, habit-tic deformity, and traumatic median splits (Elewski \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Tosti et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Alessandrini et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Inthasot et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Rachadi and Chiheb \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Accurate identification of the central canal with symmetric lateral ridging is essential to avoid unnecessary antifungal therapy or invasive procedures. Onychomycosis is usually accompanied by chromonychia, subungual debris, and nail thickening (Elewski \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). Habit-tic deformity presents with transverse ridges and proximal nail fold damage (Alessandrini et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Nail lichen planus exhibits pterygium formation, progressive thinning, and periungual inflammation (Tosti et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), whereas traumatic splits correlate with localized injury history (Inthasot et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDermoscopy can serve as a noninvasive diagnostic adjunct, revealing a central groove with regularly arranged lateral fissures, parallel whitish lines, and distal nail plate splitting (Satish et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Pauliņa and Balcere \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Alessandrini et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Dermoscopic evaluation may help distinguish MCDH from infectious or inflammatory nail disorders, though it was not performed in this patient.\u003c/p\u003e \u003cp\u003e Management lacks standardized guidelines. Conservative measures, including patient education and avoidance of microtrauma or habitual manipulation, remain first-line (Satish et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Spontaneous improvement has been reported, though some cases remain stable for years. Anecdotal treatments include topical tacrolimus (Kim et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2010\u003c/span\u003e), intralesional corticosteroids, and Nd:YAG laser therapy (Choi et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). In this case, conservative management with reassurance was appropriate and effective.\u003c/p\u003e \u003cp\u003eThis report highlights important clinical points: MCDH can involve multiple nails including toenails even without clear triggers, clinical assessment can establish diagnosis without unnecessary tests, and recognition of atypical presentations prevents misdiagnosis and overtreatment. Limitations include the absence of dermoscopic examination and mycologic testing, which could provide additional diagnostic confirmation in atypical or progressive cases. Future studies should clarify pathophysiology, risk factors, and optimal management strategies.\u003c/p\u003e \u003cp\u003eOverall, this case further expands the clinical spectrum of MCDH, emphasizing that idiopathic multinail involvement is possible and reinforcing the value of accurate diagnosis and patient counseling (Li and Shou \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Saddik et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eMedian canaliform dystrophy of Heller (MCDH) is a rare, benign nail matrix disorder that may occasionally involve multiple nails. This case demonstrates an idiopathic presentation with bilateral thumbnail and left great toenail involvement in a young adult male without identifiable risk factors. Clinical recognition of atypical presentations is essential to prevent misdiagnosis, avoid unnecessary diagnostic testing, and reduce inappropriate interventions. Conservative management with patient education and reassurance remains the mainstay of care for asymptomatic cases.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMCDH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMedian Canaliform Dystrophy of Heller\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eCompeting Interests\u003c/strong\u003e \u003cp\u003eThe author declares no competing interests.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eEthics Approval\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to Participate\u003c/strong\u003e \u003cp\u003e Written informed consent was obtained from the patient for publication of this case report and accompanying images.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eReporting Guidelines\u003c/h2\u003e \u003cp\u003e This report was prepared in accordance with the CARE guidelines.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eAuthor Contributions Statement\u003c/h2\u003e \u003cp\u003eJ.R. conceived the study, collected and interpreted the clinical data, prepared all figures and tables, and wrote and revised the manuscript. J.R. approved the final version for submission and takes responsibility for all aspects of the work.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eNo funding was received.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.R. conceived the study, collected and interpreted the clinical data, prepared all figures and tables, and wrote and revised the manuscript. J.R. approved the final version for submission and takes responsibility for all aspects of the work.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThe author thanks the patient for consent and cooperation\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e \u003cp\u003eAll relevant data are included within the article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAlessandrini A, Starace M, Piraccini BM. Dermoscopy in the Evaluation of Nail Disorders. Skin Appendage Disord. 2017;3:70\u0026ndash;82. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1159/000458728\u003c/span\u003e\u003cspan address=\"10.1159/000458728\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChoi J-Y, Seo H-M, Kim W-S. Median canaliform nail dystrophy treated with a 1064-nm quasi-long pulsed Nd:YAG laser. J Cosmet Laser Ther. 2017;17:225\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/14764172.2017.1279330\u003c/span\u003e\u003cspan address=\"10.1080/14764172.2017.1279330\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eElewski BE. Onychomycosis: pathogenesis, diagnosis, and management. Clin Microbiol Rev. 1998;11:415\u0026ndash;29. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1128/cmr.11.3.415\u003c/span\u003e\u003cspan address=\"10.1128/cmr.11.3.415\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInthasot S, Andr\u0026eacute; J, Richert B. Causes of longitudinal nail splitting: a retrospective 56-case series with clinical pathological correlation. J Eur Acad Dermatol Venereol. 2022;36:744\u0026ndash;53. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/jdv.17967\u003c/span\u003e\u003cspan address=\"10.1111/jdv.17967\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim BY, Jin SP, Won C-H, Cho S. Treatment of median canaliform nail dystrophy with topical 0.1% tacrolimus ointment. J Dermatol. 2010;37:573\u0026ndash;4. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.1346-8138.2009.00769.x\u003c/span\u003e\u003cspan address=\"10.1111/j.1346-8138.2009.00769.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi S-Q, Shou Y. Median canaliform dystrophy of Heller. QJM. 2025;118:925. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/qjmed/hcaf133\u003c/span\u003e\u003cspan address=\"10.1093/qjmed/hcaf133\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLitaiem N, Mnif E, Zeglaoui F. Dermoscopy of Onychomycosis: A Systematic Review. Dermatol Pract Concept. 2023;13:e2023072. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5826/dpc.1301a72\u003c/span\u003e\u003cspan address=\"10.5826/dpc.1301a72\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePauliņa LA, Balcere A. Median Nail Canaliform Dystrophy in Association with Retinoid Therapy. Dermatol Pract Concept. 2023;13:2023184. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.5826/dpc.1303a184\u003c/span\u003e\u003cspan address=\"10.5826/dpc.1303a184\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePathania V. Median Canaliform Dystrophy of Heller occurring on thumb and great toe nails. Med J Armed Forces India. 2016;72:178\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.mjafi.2015.06.020\u003c/span\u003e\u003cspan address=\"10.1016/j.mjafi.2015.06.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRachadi H, Chiheb S. Dermoscopic features of nail psoriasis: a systematic review. Int J Dermatol. 2024;63:1013\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/ijd.17138\u003c/span\u003e\u003cspan address=\"10.1111/ijd.17138\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRaizada A, Panda M, Behera D, Raj C. Stress associated median canaliform dystrophy of Heller; more prominent on dominant thumb. Our Dermatol Online. 2020;11:44\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.7241/ourd.20201.10\u003c/span\u003e\u003cspan address=\"10.7241/ourd.20201.10\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRichert B, Caucanas M, Andr\u0026eacute; J. Diagnosis using nail matrix. Dermatol Clin. 2015;33:243\u0026ndash;55. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.det.2014.12.005\u003c/span\u003e\u003cspan address=\"10.1016/j.det.2014.12.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaddik A, El Fatoiki FZ, Skali H, et al. Bilateral median canaliform dystrophy of Heller of both toenails in a child. Int J Clin Med Case Rep. 2023. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.46998/IJCMCR.2023.23.000573\u003c/span\u003e\u003cspan address=\"10.46998/IJCMCR.2023.23.000573\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSatish J, Sanjana J, Gawali S, et al. Dermoscopy of Median Canaliform Dystrophy: A Rare Entity. Clin Dermatol Rev. 2025;9:104\u0026ndash;5. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4103/cdr.cdr_75_24\u003c/span\u003e\u003cspan address=\"10.4103/cdr.cdr_75_24\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSweeney SA, Cohen PR, Schulze KE, Nelson BR. Familial median canaliform nail dystrophy. Cutis. 2005;75:161\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTosti A, Piraccini BM, Iorizzo M. Nail lichen planus and other inflammatory nail disorders. Dermatol Clin. 2006;24:341\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.det.2006.03.007\u003c/span\u003e\u003cspan address=\"10.1016/j.det.2006.03.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang C, Lee S, Howard A, Foley P. Coexisting median canaliform nail dystrophy and habit-tic deformity in a patient with atopic dermatitis. Australas J Dermatol. 2020;61:100\u0026ndash;1. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/ajd.13084\u003c/span\u003e\u003cspan address=\"10.1111/ajd.13084\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-rare-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Journal of Rare Diseases](https://link.springer.com/journal/44162)","snPcode":"44162","submissionUrl":"https://submission.nature.com/new-submission/44162/3","title":"Journal of Rare Diseases","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Medial canaliform dystrophy, Nail matrix disorder, Nail dystrophy, Fir-tree nail deformity, Multinail involvement.","lastPublishedDoi":"10.21203/rs.3.rs-8971252/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8971252/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eMedian canaliform dystrophy of Heller (MCDH) is a rare nail matrix disorder typically affecting one or both thumbnails. Multinail involvement, including toenails, is rarely reported. We describe a case with atypical multi-digit involvement to broaden the recognized clinical spectrum.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA 29-year-old male underwent dermatologic evaluation for chronic, asymptomatic nail deformities of both thumbnails and the left great toenail. Diagnosis was made clinically based on characteristic morphology after systematically excluding onychomycosis, habit-tic deformity, and inflammatory nail disorders.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eExamination revealed central longitudinal canals with symmetric oblique lateral ridging forming a fir-tree pattern. Periungual tissues were normal, and there was no history of trauma, manipulation, systemic disease, or medication exposure. A clinical diagnosis of MCDH was established. The patient was managed conservatively with reassurance and advice to avoid microtrauma. At six-month follow-up, nail changes were stable and asymptomatic; the patient reported understanding the benign nature of the condition.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eThis case demonstrates an uncommon idiopathic presentation of MCDH involving bilateral thumbnails and a toenail. Awareness of such atypical presentations can prevent misdiagnosis, unnecessary testing, and inappropriate interventions.\u003c/p\u003e","manuscriptTitle":"Atypical Multinail Median Canaliform Dystrophy of Heller with Toenail Involvement: A Case Report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-26 02:57:59","doi":"10.21203/rs.3.rs-8971252/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-03T04:19:03+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-02T18:27:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-28T17:46:51+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"197247711614559033753348470194440340663","date":"2026-03-23T13:52:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"122722724411414366025417199923326401034","date":"2026-03-20T13:58:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"252356858504468640189568372996070233684","date":"2026-03-20T12:49:51+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-20T10:54:41+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-03T14:02:59+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-03T13:58:56+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Rare Diseases","date":"2026-02-25T20:59:12+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-rare-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Journal of Rare Diseases](https://link.springer.com/journal/44162)","snPcode":"44162","submissionUrl":"https://submission.nature.com/new-submission/44162/3","title":"Journal of Rare Diseases","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a6062858-1f6a-46bc-b40d-27fb5d2441aa","owner":[],"postedDate":"March 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-09T07:26:57+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-26 02:57:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8971252","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8971252","identity":"rs-8971252","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}