Isolated Right Ventricular Hypertrophic Cardiomyopathy Mimicking an Intramural Mass in a 13-Year-Old Male

Isolated Right Ventricular Hypertrophic Cardiomyopathy Mimicking an Intramural Mass in a 13-Year-Old Male | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Clinical Case Reports This is a preprint and has not been peer reviewed. Data may be preliminary. 1 September 2025 V1 Latest version Share on Isolated Right Ventricular Hypertrophic Cardiomyopathy Mimicking an Intramural Mass in a 13-Year-Old Male Authors : Hu Tingting 0009-0001-1534-6878 , Yongtai Liu [email protected] , Guotao Ma , Li Xiaona , and Shi Ximin Authors Info & Affiliations https://doi.org/10.22541/au.175672574.47187859/v1 Published Clinical Case Reports Version of record Peer review timeline 216 views 168 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Hypertrophic cardiomyopathy (HCM) typically involves the left ventricle. While right ventricular hypertrophy may occasionally coexist, severe right ventricular hypertrophy or right ventricular outflow tract (RVOT) obstruction is rare, with unclear incidence. Isolated right ventricular HCM has only been reported in individual cases. Here, we present a case of RVOT-type HCM. Case Image Isolated Right Ventricular Hypertrophic Cardiomyopathy Mimicking an Intramural Mass in a 13-Year-Old Male Hu Tingting 1 , Ma Guotao 2 , Li Xiaona 3 , Shi Ximin 4 , Liu Yongtai 1 1 Department of Cardiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences , 2 Department of Cardiac Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences , 3 Department of Pathology Peking Union Medical College Hospital, Chinese Academy of Medical Sciences , 4 Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences Corresponding author: Liu Yongtai, E-mail: [email protected] Key words: Hypertrophic cardiomyopathy；Right Ventricular Outflow Tract; Mimicking mass Key Clinical Message Hypertrophic cardiomyopathy (HCM) typically involves the left ventricle. While right ventricular hypertrophy may occasionally coexist, severe right ventricular hypertrophy or right ventricular outflow tract (RVOT) obstruction is rare, with unclear incidence. Isolated right ventricular HCM has only been reported in individual cases. Here, we present a case of RVOT-type HCM. Case presentation A 13-year-old male presented with chest tightness and dyspnea for over six months without obvious inciting factors, occasionally accompanied by non-exertional chest pain. He reported preserved functional capacity (running, climbing three flights of stairs) and no orthopnea at night, denying radiating pain, limb edema, cough, or hemoptysis. The electrocardiogram (ECG) （Figure1）shows sinus rhythm, with a RS r’s’ pattern in lead V1, R/S ratio greater than 1, and biphasic T waves in leads V1 to V3. Transthoracic echocardiography（Figure2-Figure4） identified a well-circumscribed 44×25 mm homogeneous mid-level echogenic mass within the anterior wall of the right ventricular outflow tract (RVOT), with preserved RVOT hemodynamics (peak velocity 1.4 m/s) and global systolic function (left ventricular ejection fraction 66%,right ventricular area change fraction 48%，tricuspid annular plane systolic excursion 18mm). Cardiac magnetic resonance imaging (CMR) with contrast revealed a broad-based, fusiform soft-tissue lesion in the superior part of the RVOT anterior wall, characterized by isointensity on T1-weighted imaging, mild hypointensity on T2-weighted and T2-TIRM sequences, with scattered focal areas of markedly low signal intensity within the myocardium (likely attributable to vascular flow-void artifacts). First-pass perfusion imaging demonstrated heterogeneous enhancement with prominent peripheral hyperemia, while delayed gadolinium enhancement revealed patchy areas of significant enhancement within the lesion during the delayed phase. Positron emission tomography-computed tomography (PET-CT) (Figure5) showed a 3.7×2.4×3.3 cm hypermetabolic mass in the RVOT region with a maximum standard uptake value (SUV max) of 7.8, indicative of increased glucose metabolism. The patient was diagnosed with an intramural mass in the right ventricle (with malignancy not excluded), and underwent surgical intervention. Intraoperative Findings: The mass was observed protruding into the right ventricular outflow tract (RVOT), with firm and tough consistency on palpation. The thickest segment of the mass, measuring 2 cm in thickness, was located at the midpoint. A 1.5cm longitudinal incision was made along the lateral edge of the interventricular groove toward the mass midpoint, revealing a cut surface without gross morphological difference from the adjacent myocardium，frozen section analysis revealed myocardial tissue, leading to a diagnosis of hypertrophic cardiomyopathy. So the thickened myocardium was subsequently resected to a target thickness of ~1 cm. Specimens were processed using standard FFPE (formalin-fixed paraffin-embedded) protocol: fixed in 10% neutral formalin, dehydrated through gradient ethanol, cleared in xylene, embedded in paraffin, sectioned at 4-μm thickness, and stained with Hematoxylin and Eosin (H&E). Microscopic examination（Figure6） revealed myocardial tissue with focal myocardial cell hyperplasia, with scattered adipose tissue and thick-walled muscular blood vessels among myocardial fibers. Immunohistochemistry: SMA (-), Desmin (+), S-100 (-), CD31 (+), CD34 (+). Special stains ：elastic fibers (-) ， Gomori methenamine silver (-). Figure 1: The admission electrocardiogram shows sinus rhythm, with a RSr’s’ pattern in lead V1, R/S ratio greater than 1, and biphasic T waves in leads V1 to V3. The original image was defaced, and this is the restored version. Figure 2: Parasternal long-axis view of echocardiography showing focal thickening of the anterior wall of the right ventricular outflow tract (RVOT) (red arrow). LV: left ventricle; RVOT: right ventricular outflow tract; LA: left atrium; AO: aorta. Figure 3: Parasternal right ventricular inflow tract view demonstrates focal thickening of the right ventricular anterior wall (red arrow), with vascular structures traversing through it (green dashed arrow). RV: right ventricle; RA: right atrium. Figure 4: Parasternal short-axis view of the great arteries showing focal thickening of the right ventricle anterior wall (red arrow), with vascular structures traversing through it (green dashed arrow). The figure caption is the same as in Figures 2 and 3. Figure 5：PET/CT showed focally increased F-FDG uptake (SUV max = 7.8) in the RVOT region (red arrow)（red arrow）. Figure 6：The surgical pathological specimen (H&E staining, ×20) revealed myocardial tissue with hyperplastic myocardial cells, along with scattered muscular thick-walled blood vessels (black arrow) and adipose tissue (yellow arrow) interspersed among the myocardial fibers. Discussion Right ventricular hypertrophy (RVH) occurs in 28%-44% of hypertrophic cardiomyopathy (HCM) patients [1] , mostly in association with left ventricular hypertrophy. Isolated RVOT-HCM without LV involvement is extremely rare, with fewer than 20 reported cases in the literature to date [2,3] . Preoperative imaging in this case demonstrated a space-occupying effect in the RVOT with imaging features mimicking malignancy: homogeneous echogenicity on echo, T2-hypointensity on CMR, peripheral hyperemia on perfusion, and notably high FDG uptake (SUV=7.8) on PET-CT. Postoperative pathology, however, confirmed myocardial tissue with myocyte hypertrophy in this region. Increased glucose uptake may reflect myocardial ischemia due to microvascular dysfunction, as proposed by Marques-Alves et al [4] , rather than malignant transformation. This may represent pre-fibrotic early pathological changes or be associated with the patient’s younger age [5] . A key diagnostic clue was the intraoperative finding of lesion continuity with normal myocardium, prompting frozen section analysis that prevented unnecessary radical resection. The patient’s symptoms resolved at 3 months postoperatively, but long-term follow-up data is unavailable, which was a limitation of this report. The cardiac MRI was performed at another hospital, and the electronic images were unavailable，which was another limitation. This case reminded us that RVOT evaluation should be considered in adolescent patients with exertional dyspnea even if standard echocardiography was unremarkable，and isolated right ventricular hypertrophic cardiomyopathy must be considered in the differential diagnosis of right ventricular intramural masses, particularly when intraoperative findings suggest myocardial continuity. A telephone follow-up conducted one year postoperatively revealed that the patient was in good general condition with no recurrence of specific symptoms. Written informed consent has been obtained from the patient. All authors declare that they have no conflicts of interest. Author Contributions: Hu Tingting: Participated in the study design; collected the patient’s clinical data (including medical history and echocardiographic results) and follow-up information; analyzed and interpreted the clinical data; drafted the initial manuscript; made important revisions to the core content of the manuscript; gave final approval of the version to be published; and took responsibility for all aspects of the study. Liu Yongtai: Initiated and supervised the entire study; provided core guidance on study design and data interpretation; revised the manuscript for content and language accuracy; ensured that all authors met the ICMJE authorship criteria; gave final approval of the version to be published; and served as the corresponding author for all inquiries related to this study. Ma Guotao: Participated in the formulation of the patient’s preoperative surgical plan and decided on modifications to the surgical plan during the operation; provided intraoperative findings and surgical records; participated in discussions on the patient’s diagnosis and treatment plan; revised the surgery-related content in the manuscript; and gave final approval of the version to be published. Li Xiaona: Analyzed the specimen of the cardiac space-occupying lesion; interpreted the pathological results and issued the pathological diagnosis report; provided pathological images and descriptions for the manuscript; participated in the confirmation of the final diagnosis; revised the pathology-related content in the manuscript; and gave final approval of the version to be published. Shi Ximin: Performed and interpreted the patient’s PET-CT examination; analyzed imaging features (such as myocardial metabolism and structural changes) and issued the imaging diagnosis report; selected and organized key PET-CT images for the manuscript; confirmed the consistency between imaging results and clinical diagnosis; revised the imaging-related content in the manuscript; and gave final approval of the version to be published. References [1] Berger SG, Sjaastad I, Stokke MK. Right ventricular involvement in hypertrophic cardiomyopathy: evidence and implications from current literature. Scand Cardiovasc J. 2021;55(4):195-204. doi:10.1080/14017431.2021.1901979 [2] Mittal SR, Jain S. Isolated right ventricular hypertrophic obstructive cardiomyopathy. J Assoc Physicians India. 1998; 46:970-971. [3] Shako D, Kawasaki T, Yamano M, Matoba S. Isolated extreme right ventricular hypertrophy: A case report. J Cardiol Cases. 2021;24(4):195-204. doi:10.1016/j. jccase.2021.07.001. [4] Marques-Alves P, Gonçalves L, João M. PET-CT imaging in hypertrophic cardiomyopathy: a narrative review on risk stratification and prognosis. Diagnostics. 2025;15(2):133. doi:10.3390/diagnostics15020133. [5] Kagaya Y, Ishide N, Takeyama D, et al. Differences in myocardial fluoro-18 2-deoxyglucose uptake in young versus older patients with hypertrophic cardiomyopathy. Am J Cardiol. 1992; 69:242-246. Information & Authors Information Version history V1 Version 1 01 September 2025 Peer review timeline Published Clinical Case Reports Version of Record 15 Jan 2026 Published Copyright This work is licensed under a Non Exclusive No Reuse License. Collection Clinical Case Reports Keyword cardiology Authors Affiliations Hu Tingting 0009-0001-1534-6878 Peking Union Medical College Hospital View all articles by this author Yongtai Liu [email protected] Peking Union Medical College Hospital View all articles by this author Guotao Ma Peking Union Medical College Hospital View all articles by this author Li Xiaona Peking Union Medical College Hospital View all articles by this author Shi Ximin Peking Union Medical College Hospital View all articles by this author Metrics & Citations Metrics Article Usage 216 views 168 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Hu Tingting, Yongtai Liu, Guotao Ma, et al. Isolated Right Ventricular Hypertrophic Cardiomyopathy Mimicking an Intramural Mass in a 13-Year-Old Male. Authorea . 01 September 2025. 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