Black Hairy Tongue vs. Mucormycosis in Dialysis: A Case Report of Statin- Associated Lesion and 7-Day Resolution

Black Hairy Tongue vs. Mucormycosis in Dialysis: A Case Report of Statin- Associated Lesion and 7-Day Resolution | 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 Black Hairy Tongue vs. Mucormycosis in Dialysis: A Case Report of Statin- Associated Lesion and 7-Day Resolution Majd Werda, Chadha Ben Amar, Ons Belhadj, Moncef Sellami, Ilheme Charfeddine This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6842349/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Black hairy tongue (BHT), while typically benign, presents significant diagnostic challenges in immunocompromised patients where it may mimic life-threatening conditions like mucormycosis. This case is noteworthy due to its exceptionally rapid onset in a high-risk patient and its association with statin therapy, a rarely reported trigger. The clinical urgency of distinguishing BHT from malignant or invasive fungal processes in vulnerable populations makes this report particularly valuable to the medical community. Case presentation A 73-year-old male with end-stage renal disease (on hemodialysis), poorly controlled diabetes mellitus, and long-term atorvastatin use developed dramatic black discoloration of the tongue over 24 hours. Physical examination revealed characteristic elongated, hyperpigmented filiform papillae without evidence of necrosis or ulceration. The patient denied pain but reported significant cosmetic concern. Diagnostic workup included an urgent tongue biopsy which showed reactive hyperkeratosis with Candida species colonization, definitively excluding mucormycosis or malignant transformation. Management consisted of three key interventions: discontinuation of atorvastatin, implementation of twice-daily mechanical debridement using a soft toothbrush, and strict avoidance of tobacco products. Remarkably, complete resolution occurred within seven days without requiring antifungal therapy. Conclusions This case highlights three crucial clinical lessons: first, the critical importance of histopathological confirmation in immunocompromised patients presenting with rapid tongue discoloration to rule out sinister pathology; second, the potential role of statins in triggering acute BHT onset, suggesting temporary discontinuation may accelerate resolution; and third, the demonstrated efficacy of conservative measures alone in managing even dramatic presentations of BHT, avoiding unnecessary antimicrobial use. These findings have immediate practical implications for clinicians managing high-risk patients with similar presentations. Black hairy tongue mucormycosis dialysis statins Figures Figure 1 Introduction Black hairy tongue (BHT) is a benign condition characterized by elongation and hyperpigmentation of filiform papillae, often linked to antibiotic use (Ren et al. 2020 ; Sakaguchi & Watari 2020 ; Niiyama & Hase 2021 ; Okumura & Kawashima 2023 ), smoking, or poor oral hygiene (Jayasree, Kaliyadan & Ashique 2022 ). While typically asymptomatic, its dramatic appearance can mimic serious conditions like mucormycosis, particularly in immunocompromised patients (Y.-P. Chen et al. 2021 ). Antibiotics, including tetracyclines (Sakaguchi & Watari 2020 ), linezolid (Shangguan et al. 2022 ), and metronidazole (Niiyama & Hase 2021 ), are well-documented triggers, but other medications such as statins, lithium (Selvakumar et al. 2016 ), and antitubercular drugs (Leo, Semper & Grohé 2022) have also been implicated. BHT is rare in dialysis patients, though uremia and immunosuppression may predispose to its development (T.-H. Chen et al. 2021 ). Management focuses on eliminating causative agents (Okumura & Kawashima 2023 ; Fahdawi, Aung & Iqbal 2024 ) and mechanical debridement (Kuo, Chen & Wu 2023 ), with most cases resolving within weeks (Ren et al. 2020 ). However, its rapid onset in high-risk populations—such as those with end-stage renal disease (T.-H. Chen et al. 2021 ) or multidrug-resistant infections (Leo et al. 2022)—can lead to unnecessary invasive testing due to clinical overlap with fungal infections (Shangguan et al. 2022 ; Salas-Alanís et al. 2025 ). This case highlights BHT’s diagnostic challenges in comorbid patients and underscores the importance of recognizing medication-induced variants to avoid overtreatment. Case Presentation A 73-year-old male with end-stage renal disease (hemodialysis 3×/week for 10 years), insulin-dependent diabetes mellitus (5 years), hypertension (on calcium channel blockers), and dyslipidemia (atorvastatin for 10 years) presented with acute-onset blackish dorsal tongue discoloration progressing rapidly over 24 hours (Fig. 1). He reported significant distress but denied dysgeusia, odynophagia, dysphagia, or respiratory symptoms. Physical examination revealed an afebrile patient with no odontogenic infection or oral lesions, and indirect laryngoscopy showed normal laryngeal anatomy. Given his immunocompromised status (long-term hemodialysis and poorly controlled diabetes) and high mucormycosis risk, a diagnostic workup was initiated. Tongue biopsy under local anesthesia demonstrated reactive filiform hyperkeratosis without fungal elements, dysplasia, or malignancy, confirmed by mycological examination excluding invasive fungal infection. Differential diagnoses included black hairy tongue (confirmed by histopathology), oral mucormycosis (ruled out by absent hyphae), candidiasis (excluded via mycological testing), and melanocytic lesions (no atypia on histology). Management involved twice-daily mechanical debridement with a soft toothbrush, tongue scraping, and avoidance of tobacco, alcohol, black tea/coffee, and oxidizing mouthwashes. Atorvastatin was temporarily discontinued after cardiology consultation due to its potential role in the condition. Complete resolution of tongue discoloration occurred within one week. Discussion This case highlights several clinically relevant aspects of black hairy tongue (BHT) in high-risk populations. While typically benign, the rapid progression in our immunocompromised dialysis patient necessitated thorough evaluation to exclude life-threatening mimics like mucormycosis (T.-H. Chen et al. 2021 ; Salas-Alanís et al. 2025 ), particularly given the concerning visual presentation that often prompts biopsy (Jayasree et al. 2022 ). The absence of fungal elements on both histopathology and mycological examination (Niiyama & Hase 2021 ; Shangguan et al. 2022 ) reinforced BHT’s diagnostic challenge in comorbid patients, where clinical suspicion for opportunistic infections remains high (Ren et al. 2020 ; Leo et al. 2022). Notably, our patient’s long-term atorvastatin use may have contributed to pathogenesis, as statins and other medications (Selvakumar et al. 2016 ; Sakaguchi & Watari 2020 ; Okumura & Kawashima 2023 ) are increasingly recognized triggers through unclear mechanisms—possibly via altered keratinocyte turnover or microbial flora changes (Shangguan et al. 2022 ; Fahdawi et al. 2024 ). This association warrants attention given statins’ widespread use, though only isolated cases have been reported (Selvakumar et al. 2016 ). The swift resolution following statin discontinuation and conservative measures aligns with literature emphasizing trigger avoidance as cornerstone therapy (Kuo et al. 2023 ; Okumura & Kawashima 2023 ; Fahdawi et al. 2024 ), though the 1-week recovery was unusually rapid compared to typical 2–4 weeks’ timelines (Ren et al. 2020 ). Mechanical debridement’s efficacy (Kuo et al. 2023 ) likely synergized with removing pharmacological triggers, a strategy particularly crucial in dialysis patients who may have heightened susceptibility due to uremia-related mucosal changes (T.-H. Chen et al. 2021 ). While antibiotic-induced BHT is well-documented (Ren et al. 2020 ; Sakaguchi & Watari 2020 ; Niiyama & Hase 2021 ), our case expands the differential to include statins in renal impairment contexts, where polypharmacy is common. The lack of recurrence at follow-up supports transient drug effects over permanent structural changes (Chinnappan & Vetripandian 2023 ; Shah & Hegde 2024 ). Clinicians should consider BHT in differentials for acute tongue pigmentation, even in immunocompromised hosts, as premature antifungal therapy can be avoided through targeted biopsy (Salas-Alanís et al. 2025 ). Future studies might explore statins’ role in BHT pathogenesis, especially in renally impaired populations where drug metabolism is altered (Chakraborty & Pulai 2013 ; T.-H. Chen et al. 2021 ). Conclusion Black hairy tongue (BHT), though benign, can closely mimic life-threatening mucormycosis in immunocompromised patients, mandating histopathological confirmation to exclude invasive fungal infection or malignancy (T.-H. Chen et al. 2021 ; Jayasree et al. 2022 ; Salas-Alanís et al. 2025 ). This case underscores that statin therapy may precipitate rapid-onset BHT, and temporary discontinuation—following multidisciplinary consultation—can accelerate resolution while mitigating recurrence risks (Selvakumar et al. 2016 ; Okumura & Kawashima 2023 ). Conservative management with mechanical debridement (tongue brushing) and avoidance of predisposing factors achieves reliable outcomes even in high-risk populations like dialysis patients, obviating unnecessary antifungals (T.-H. Chen et al. 2021 ; Kuo et al. 2023 ; Fahdawi et al. 2024 ). Crucially, comprehensive medication review is indispensable in BHT management, particularly for renal patients with polypharmacy, as pharmacologic triggers are frequently overlooked (Chakraborty & Pulai 2013 ; T.-H. Chen et al. 2021 ). The presented clinical trajectory reaffirms that dramatic presentation timelines (e.g., 24-hour progression) do not invariably signify infection, emphasizing histopathology’s irreplaceable role in differential diagnosis (Jayasree et al. 2022 ; Salas-Alanís et al. 2025 ). Declarations Ethics approval and consent to participate Ethical approval was obtained from the medical ethics committee of the Faculty of Medicine of Sfax, Tunisia. The committee does not attribute an approval number for case reports, as per institutional guidelines. Consent for publication Written informed consent was obtained from the patient for publication of this case report and any accompanying data or images. Availability of data and material The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Authors' contributions Majd Werda: Conceptualization, Methodology, Validation, Investigation, Resources, Data curation, Formal analysis, Visualization, Project administration, Supervision, Writing – original draft, Writing – review & editing. Chadha Ben Amar: Methodology, Validation, Investigation, Resources, Data curation, Formal analysis, Writing – review & editing. Ons Belhadj: Investigation, Resources, Validation, Visualization (histopathological analysis), Writing – review & editing. Moncef Sellami: Methodology, Supervision, Validation, Writing – review & editing. Ilheme Charfeddine: Conceptualization, Methodology, Supervision, Validation, Writing – review & editing. All authors read and approved the final manuscript. Acknowledgements Not applicable. References Chakraborty PP, Pulai D. Black hairy tongue (lingua villosa nigra). J Assoc Physicians India. 2013;61(12):908. Chen TH, Yu HT, Wu CH, Lin CC. Black hairy tongue in an end-stage renal disease patient. J Formos Med Assoc. 2021;120(7):1531–2. Chen YP, Liu X, Zhou Q, et al. Metronomic capecitabine as adjuvant therapy in locoregionally advanced nasopharyngeal carcinoma: a multicentre, open-label, parallel-group, randomised, controlled, phase 3 trial. Lancet. 2021;398(10297):303–13. Chinnappan S, Vetripandian M. Lingua Villosa Nigra. Indian Pediatr. 2023;60(1):159. Fahdawi A, Aung ZY, Iqbal MS. A Case Report of a Co-Amoxiclav-Induced Black Hairy Tongue. Cureus. 2024;16(4):e58657. Jayasree P, Kaliyadan F, Ashique KT. Black Hairy Tongue. JAMA Dermatol. 2022;158(5):573. Kuo PY, Chen PH, Wu SH. Black hairy tongue treated with traditional Chinese medicine: A case report. Medicine (Baltimore). 2023;102(43):e34430. Leo F, Semper H, Grohé C. Lingua villosa nigra following initiation of antibiotic treatment for multidrug-resistent tuberculosis. Dtsch Arztebl Int. 2022 Nov 4 [cited 2025 Apr 15]. Available from: https://www.aerzteblatt.de/ 10.3238/arztebl.m2022.0211 Niiyama Y, Hase R. Black hairy tongue caused by metronidazole. Braz J Infect Dis. 2021;25(5):101633. Okumura H, Kawashima A. Black hairy tongue due to antibiotics. BMJ Case Rep. 2023;16(7):e255112. Ren J, Zheng Y, Du H, et al. Antibiotic-induced black hairy tongue: two case reports and a review of the literature. J Int Med Res. 2020;48(10):0300060520961279. Sakaguchi K, Watari T. Tetracycline-induced black hairy tongue. J Gen Fam Med. 2020;21(3):80–1. Salas-Alanís JC, Salas-Garza M, Moreno-Treviño MG, et al. Black hairy tongue. Med Clin (Barc). 2025;164(7):386–7. Shangguan Y, Ji Z, Guo W, et al. Oral Bacteria Dysbiosis in Patients with Linezolid-Induced Black Hairy Tongue: A Case Series. Infect Drug Resist. 2022;15:5449–54. Shah S, Hegde SS. Lingua villosa nigra in an infant. Indian J Dermatol Venereol Leprol. 2024;90:804–6. Selvakumar N, Selvapandian Thamizh J, Menon V, Rajkumar RP. Black hairy tongue (Lingua villosa nigra) in a young male precipitated by Lithium. Asian J Psychiatry. 2016;24:71–2. Additional Declarations No competing interests reported. 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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-6842349","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":487761171,"identity":"26594d8a-63f1-4417-bb65-12f09447f1e1","order_by":0,"name":"Majd Werda","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA30lEQVRIiWNgGAWjYJACCSBmZjjeAKQMLEjRcuYASIsE8VoYGG4kINh4gcHx3oc3fubYsfPdfH51w48CCQb+9u4E/FrOHDe27N2WzCx5O6fsZg/QYRJnzm7Aq8XsRhqbBO82ZmaD2zlpN3iAWgwkcglouf+MTfLvtnpmg5tn0m7+IUrLDTY2ad5th5kNbrAfu02ULfZn0pitZbcdZ5Y8k8N2W8ZAgoegXyTbjzHefLutOpnv+PFnN9/8sZHjb+/FrwUGkhkYeAxADB6ilIOAHQMD+wOiVY+CUTAKRsHIAgAnWkhlm4zhhQAAAABJRU5ErkJggg==","orcid":"","institution":"Habib Bourguiba University Hospital","correspondingAuthor":true,"prefix":"","firstName":"Majd","middleName":"","lastName":"Werda","suffix":""},{"id":487761172,"identity":"922c8d57-0dc4-458e-b91a-5b26bc2873a6","order_by":1,"name":"Chadha Ben Amar","email":"","orcid":"","institution":"Habib Bourguiba University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chadha","middleName":"Ben","lastName":"Amar","suffix":""},{"id":487761175,"identity":"77d12e5c-2e73-4160-8fb2-99eb5a54a10e","order_by":2,"name":"Ons Belhadj","email":"","orcid":"","institution":"Habib Bourguiba University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ons","middleName":"","lastName":"Belhadj","suffix":""},{"id":487761176,"identity":"e022a7e9-e33a-4827-86b0-6170762053c9","order_by":3,"name":"Moncef Sellami","email":"","orcid":"","institution":"Habib Bourguiba University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Moncef","middleName":"","lastName":"Sellami","suffix":""},{"id":487761178,"identity":"787a13de-d0d3-401b-8a99-5800ad33ea14","order_by":4,"name":"Ilheme Charfeddine","email":"","orcid":"","institution":"Habib Bourguiba University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Ilheme","middleName":"","lastName":"Charfeddine","suffix":""}],"badges":[],"createdAt":"2025-06-07 10:53:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6842349/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6842349/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87364119,"identity":"08d95840-ae10-47aa-a3d3-e3e5a6ccce93","added_by":"auto","created_at":"2025-07-23 06:12:15","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":80752,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eBlack hairy tongue (lingua villosa nigra) affecting the ventral tongue surface.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6842349/v1/9a9cb29f8432fb6292edfe74.jpg"},{"id":104782206,"identity":"c2978af7-ca31-4ae5-94f2-45eeb6f5f272","added_by":"auto","created_at":"2026-03-17 07:56:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":491901,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6842349/v1/d23df841-d973-49f8-9980-3a1ce0a3ed8c.pdf"},{"id":87363297,"identity":"43077998-6851-4a7d-8069-84ac83f8a5cf","added_by":"auto","created_at":"2025-07-23 06:04:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":452394,"visible":true,"origin":"","legend":"","description":"","filename":"CAREChecklistBlackHairyTongue.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6842349/v1/c40b4601ed9c202fbe80b750.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Black Hairy Tongue vs. Mucormycosis in Dialysis: A Case Report of Statin- Associated Lesion and 7-Day Resolution","fulltext":[{"header":"Introduction","content":"\u003cp\u003eBlack hairy tongue (BHT) is a benign condition characterized by elongation and hyperpigmentation of filiform papillae, often linked to antibiotic use (Ren et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Sakaguchi \u0026amp; Watari \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Niiyama \u0026amp; Hase \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Okumura \u0026amp; Kawashima \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), smoking, or poor oral hygiene (Jayasree, Kaliyadan \u0026amp; Ashique \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). While typically asymptomatic, its dramatic appearance can mimic serious conditions like mucormycosis, particularly in immunocompromised patients (Y.-P. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Antibiotics, including tetracyclines (Sakaguchi \u0026amp; Watari \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), linezolid (Shangguan et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), and metronidazole (Niiyama \u0026amp; Hase \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), are well-documented triggers, but other medications such as statins, lithium (Selvakumar et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e), and antitubercular drugs (Leo, Semper \u0026amp; Groh\u0026eacute; 2022) have also been implicated.\u003c/p\u003e\u003cp\u003eBHT is rare in dialysis patients, though uremia and immunosuppression may predispose to its development (T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Management focuses on eliminating causative agents (Okumura \u0026amp; Kawashima \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Fahdawi, Aung \u0026amp; Iqbal \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) and mechanical debridement (Kuo, Chen \u0026amp; Wu \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), with most cases resolving within weeks (Ren et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). However, its rapid onset in high-risk populations\u0026mdash;such as those with end-stage renal disease (T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) or multidrug-resistant infections (Leo et al. 2022)\u0026mdash;can lead to unnecessary invasive testing due to clinical overlap with fungal infections (Shangguan et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Salas-Alan\u0026iacute;s et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This case highlights BHT\u0026rsquo;s diagnostic challenges in comorbid patients and underscores the importance of recognizing medication-induced variants to avoid overtreatment.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA 73-year-old male with end-stage renal disease (hemodialysis 3\u0026times;/week for 10 years), insulin-dependent diabetes mellitus (5 years), hypertension (on calcium channel blockers), and dyslipidemia (atorvastatin for 10 years) presented with acute-onset blackish dorsal tongue discoloration progressing rapidly over 24 hours (Fig.\u0026nbsp;1).\u003c/p\u003e\u003cp\u003eHe reported significant distress but denied dysgeusia, odynophagia, dysphagia, or respiratory symptoms. Physical examination revealed an afebrile patient with no odontogenic infection or oral lesions, and indirect laryngoscopy showed normal laryngeal anatomy. Given his immunocompromised status (long-term hemodialysis and poorly controlled diabetes) and high mucormycosis risk, a diagnostic workup was initiated. Tongue biopsy under local anesthesia demonstrated reactive filiform hyperkeratosis without fungal elements, dysplasia, or malignancy, confirmed by mycological examination excluding invasive fungal infection. Differential diagnoses included black hairy tongue (confirmed by histopathology), oral mucormycosis (ruled out by absent hyphae), candidiasis (excluded via mycological testing), and melanocytic lesions (no atypia on histology). Management involved twice-daily mechanical debridement with a soft toothbrush, tongue scraping, and avoidance of tobacco, alcohol, black tea/coffee, and oxidizing mouthwashes. Atorvastatin was temporarily discontinued after cardiology consultation due to its potential role in the condition. Complete resolution of tongue discoloration occurred within one week.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis case highlights several clinically relevant aspects of black hairy tongue (BHT) in high-risk populations. While typically benign, the rapid progression in our immunocompromised dialysis patient necessitated thorough evaluation to exclude life-threatening mimics like mucormycosis (T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Salas-Alan\u0026iacute;s et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), particularly given the concerning visual presentation that often prompts biopsy (Jayasree et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The absence of fungal elements on both histopathology and mycological examination (Niiyama \u0026amp; Hase \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Shangguan et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) reinforced BHT\u0026rsquo;s diagnostic challenge in comorbid patients, where clinical suspicion for opportunistic infections remains high (Ren et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Leo et al. 2022). Notably, our patient\u0026rsquo;s long-term atorvastatin use may have contributed to pathogenesis, as statins and other medications (Selvakumar et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Sakaguchi \u0026amp; Watari \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Okumura \u0026amp; Kawashima \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) are increasingly recognized triggers through unclear mechanisms\u0026mdash;possibly via altered keratinocyte turnover or microbial flora changes (Shangguan et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Fahdawi et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). This association warrants attention given statins\u0026rsquo; widespread use, though only isolated cases have been reported (Selvakumar et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The swift resolution following statin discontinuation and conservative measures aligns with literature emphasizing trigger avoidance as cornerstone therapy (Kuo et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Okumura \u0026amp; Kawashima \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Fahdawi et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e), though the 1-week recovery was unusually rapid compared to typical 2\u0026ndash;4 weeks\u0026rsquo; timelines (Ren et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Mechanical debridement\u0026rsquo;s efficacy (Kuo et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) likely synergized with removing pharmacological triggers, a strategy particularly crucial in dialysis patients who may have heightened susceptibility due to uremia-related mucosal changes (T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). While antibiotic-induced BHT is well-documented (Ren et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Sakaguchi \u0026amp; Watari \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Niiyama \u0026amp; Hase \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), our case expands the differential to include statins in renal impairment contexts, where polypharmacy is common. The lack of recurrence at follow-up supports transient drug effects over permanent structural changes (Chinnappan \u0026amp; Vetripandian \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Shah \u0026amp; Hegde \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Clinicians should consider BHT in differentials for acute tongue pigmentation, even in immunocompromised hosts, as premature antifungal therapy can be avoided through targeted biopsy (Salas-Alan\u0026iacute;s et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Future studies might explore statins\u0026rsquo; role in BHT pathogenesis, especially in renally impaired populations where drug metabolism is altered (Chakraborty \u0026amp; Pulai \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eBlack hairy tongue (BHT), though benign, can closely mimic life-threatening mucormycosis in immunocompromised patients, mandating histopathological confirmation to exclude invasive fungal infection or malignancy (T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Jayasree et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Salas-Alan\u0026iacute;s et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). This case underscores that statin therapy may precipitate rapid-onset BHT, and temporary discontinuation\u0026mdash;following multidisciplinary consultation\u0026mdash;can accelerate resolution while mitigating recurrence risks (Selvakumar et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Okumura \u0026amp; Kawashima \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Conservative management with mechanical debridement (tongue brushing) and avoidance of predisposing factors achieves reliable outcomes even in high-risk populations like dialysis patients, obviating unnecessary antifungals (T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Kuo et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Fahdawi et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Crucially, comprehensive medication review is indispensable in BHT management, particularly for renal patients with polypharmacy, as pharmacologic triggers are frequently overlooked (Chakraborty \u0026amp; Pulai \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; T.-H. Chen et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The presented clinical trajectory reaffirms that dramatic presentation timelines (e.g., 24-hour progression) do not invariably signify infection, emphasizing histopathology\u0026rsquo;s irreplaceable role in differential diagnosis (Jayasree et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Salas-Alan\u0026iacute;s et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;Ethical approval was obtained from the medical ethics committee of the Faculty of Medicine of Sfax, Tunisia. The committee does not attribute an approval number for case reports, as per institutional guidelines.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;Written informed consent was obtained from the patient for publication of this case report and any accompanying data or images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' contributions\u003c/strong\u003e\u003cbr\u003e\u003cstrong\u003eMajd Werda:\u003c/strong\u003e Conceptualization, Methodology, Validation, Investigation, Resources, Data curation, Formal analysis, Visualization, Project administration, Supervision, Writing – original draft, Writing – review \u0026amp; editing.\u003cbr\u003e\u003cstrong\u003eChadha Ben Amar:\u003c/strong\u003e Methodology, Validation, Investigation, Resources, Data curation, Formal analysis, Writing – review \u0026amp; editing.\u003cbr\u003e\u003cstrong\u003eOns Belhadj:\u003c/strong\u003e Investigation, Resources, Validation, Visualization (histopathological analysis), Writing – review \u0026amp; editing.\u003cbr\u003e\u003cstrong\u003eMoncef Sellami:\u003c/strong\u003e Methodology, Supervision, Validation, Writing – review \u0026amp; editing.\u003cbr\u003e\u003cstrong\u003eIlheme Charfeddine:\u003c/strong\u003e Conceptualization, Methodology, Supervision, Validation, Writing – review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003eAll authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003cbr\u003e\u0026nbsp;Not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eChakraborty PP, Pulai D. Black hairy tongue (lingua villosa nigra). J Assoc Physicians India. 2013;61(12):908.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen TH, Yu HT, Wu CH, Lin CC. Black hairy tongue in an end-stage renal disease patient. J Formos Med Assoc. 2021;120(7):1531\u0026ndash;2.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen YP, Liu X, Zhou Q, et al. Metronomic capecitabine as adjuvant therapy in locoregionally advanced nasopharyngeal carcinoma: a multicentre, open-label, parallel-group, randomised, controlled, phase 3 trial. Lancet. 2021;398(10297):303\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChinnappan S, Vetripandian M. Lingua Villosa Nigra. Indian Pediatr. 2023;60(1):159.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFahdawi A, Aung ZY, Iqbal MS. A Case Report of a Co-Amoxiclav-Induced Black Hairy Tongue. Cureus. 2024;16(4):e58657.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJayasree P, Kaliyadan F, Ashique KT. Black Hairy Tongue. JAMA Dermatol. 2022;158(5):573.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKuo PY, Chen PH, Wu SH. Black hairy tongue treated with traditional Chinese medicine: A case report. Medicine (Baltimore). 2023;102(43):e34430.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLeo F, Semper H, Groh\u0026eacute; C. Lingua villosa nigra following initiation of antibiotic treatment for multidrug-resistent tuberculosis. Dtsch Arztebl Int. 2022 Nov 4 [cited 2025 Apr 15]. Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.aerzteblatt.de/\u003c/span\u003e\u003cspan address=\"https://www.aerzteblatt.de/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3238/arztebl.m2022.0211\u003c/span\u003e\u003cspan address=\"10.3238/arztebl.m2022.0211\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNiiyama Y, Hase R. Black hairy tongue caused by metronidazole. Braz J Infect Dis. 2021;25(5):101633.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOkumura H, Kawashima A. Black hairy tongue due to antibiotics. BMJ Case Rep. 2023;16(7):e255112.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRen J, Zheng Y, Du H, et al. Antibiotic-induced black hairy tongue: two case reports and a review of the literature. J Int Med Res. 2020;48(10):0300060520961279.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSakaguchi K, Watari T. Tetracycline-induced black hairy tongue. J Gen Fam Med. 2020;21(3):80\u0026ndash;1.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSalas-Alan\u0026iacute;s JC, Salas-Garza M, Moreno-Trevi\u0026ntilde;o MG, et al. Black hairy tongue. Med Clin (Barc). 2025;164(7):386\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShangguan Y, Ji Z, Guo W, et al. Oral Bacteria Dysbiosis in Patients with Linezolid-Induced Black Hairy Tongue: A Case Series. Infect Drug Resist. 2022;15:5449\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eShah S, Hegde SS. Lingua villosa nigra in an infant. Indian J Dermatol Venereol Leprol. 2024;90:804\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSelvakumar N, Selvapandian Thamizh J, Menon V, Rajkumar RP. Black hairy tongue (Lingua villosa nigra) in a young male precipitated by Lithium. Asian J Psychiatry. 2016;24:71\u0026ndash;2.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Black hairy tongue, mucormycosis, dialysis, statins","lastPublishedDoi":"10.21203/rs.3.rs-6842349/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6842349/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eBlack hairy tongue (BHT), while typically benign, presents significant diagnostic challenges in immunocompromised patients where it may mimic life-threatening conditions like mucormycosis. This case is noteworthy due to its exceptionally rapid onset in a high-risk patient and its association with statin therapy, a rarely reported trigger. The clinical urgency of distinguishing BHT from malignant or invasive fungal processes in vulnerable populations makes this report particularly valuable to the medical community.\u003c/p\u003e\u003ch2\u003eCase presentation\u003c/h2\u003e\u003cp\u003eA 73-year-old male with end-stage renal disease (on hemodialysis), poorly controlled diabetes mellitus, and long-term atorvastatin use developed dramatic black discoloration of the tongue over 24 hours. Physical examination revealed characteristic elongated, hyperpigmented filiform papillae without evidence of necrosis or ulceration. The patient denied pain but reported significant cosmetic concern. Diagnostic workup included an urgent tongue biopsy which showed reactive hyperkeratosis with Candida species colonization, definitively excluding mucormycosis or malignant transformation. Management consisted of three key interventions: discontinuation of atorvastatin, implementation of twice-daily mechanical debridement using a soft toothbrush, and strict avoidance of tobacco products. Remarkably, complete resolution occurred within seven days without requiring antifungal therapy.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThis case highlights three crucial clinical lessons: first, the critical importance of histopathological confirmation in immunocompromised patients presenting with rapid tongue discoloration to rule out sinister pathology; second, the potential role of statins in triggering acute BHT onset, suggesting temporary discontinuation may accelerate resolution; and third, the demonstrated efficacy of conservative measures alone in managing even dramatic presentations of BHT, avoiding unnecessary antimicrobial use. These findings have immediate practical implications for clinicians managing high-risk patients with similar presentations.\u003c/p\u003e","manuscriptTitle":"Black Hairy Tongue vs. Mucormycosis in Dialysis: A Case Report of Statin- Associated Lesion and 7-Day Resolution","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-23 06:04:10","doi":"10.21203/rs.3.rs-6842349/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"58f1cc59-84aa-4bc8-8d81-4edbd76d3934","owner":[],"postedDate":"July 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-15T22:24:08+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-23 06:04:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6842349","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6842349","identity":"rs-6842349","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}