INTRODUCTION In situ onycholemmal carcinoma, also termed atypical or malignant onychopapilloma, is an exceptionally rare nail unit neoplasm that is clinically difficult to distinguish from its benign counterpart. We report the youngest documented case of this entity and the first occurring in a patient with hereditary retinoblastoma due to a germline RB1 mutation. CASE PRESENTATION A 20-year-old woman with hereditary retinoblastoma presented with a 2-year history of progressive longitudinal erythronychia of the left second fingernail. Longitudinal excisional biopsy revealed an atypical epithelial proliferation with onycholemmal keratinization, diffuse Ki-67 expression, and negative p16 staining, consistent with in situ onycholemmal carcinoma. The lesion was successfully treated with Mohs micrographic surgery, and no recurrence was observed after 6 months. CONCLUSION This case expands the clinical spectrum of in situ onycholemmal carcinoma by demonstrating its occurrence in a young patient with a germline RB1 pathogenic variant. The findings raise the possibility of a role for RB pathway dysregulation in tumor pathogenesis and underscore the importance of maintaining a low threshold for biopsy of evolving longitudinal erythronychia, particularly in patients with inherited cancer predisposition syndromes.
ABSTRACT Acquired elastotic hemangioma is an uncommon benign cutaneous vascular proliferation first described in 2002 that typically presents as a solitary erythematous plaque arising on chronically sun-exposed skin. Histologically, it is characterized by a superficial, band-like, horizontally oriented capillary proliferation associated with marked solar elastosis. In contrast, vulvar elastosis develops in an anatomical site protected from ultraviolet radiation and has been linked to aging, hormonal changes, and inflammatory or reparative processes.In this article, we report the lesion of a 67-year-old woman with vulvar lichen sclerosus who presented with a palpable 1-cm nodule involving the left labium majus. Her medical history was notable for an undifferentiated ovarian carcinoma diagnosed 19 years earlier, treated with chemotherapy and currently in remission. Histopathological examination revealed superficial features of lichen sclerosus and, within the underlying dermis, a nodular accumulation of thick, irregular elastic fibers intermingled with numerous mature blood vessels lacking endothelial atypia.In conclusion, a prominent vascular component may represent a feature of nodular vulvar elastosis and should not necessarily be interpreted as evidence of a primary vascular neoplasm.
Abstract: Blue nevus–related lesions span a broad histopathological continuum, from benign common and cellular blue nevi to atypical cellular blue nevus and malignant blue nevus. The intermediate and malignant forms are rare, diagnostically nonstandardized and may closely mimic metastatic melanoma. We retrospectively reviewed 3 consecutive patients with rare blue nevus variants managed at a tertiary referral center between 2019 and 2025. Cases were eligible if they were histopathologically confirmed, showed diagnostic uncertainty or had initially been interpreted as metastatic melanoma, and had follow-up sufficient to assess clinical outcome. All slides were independently reviewed by 2 dermatopathologists, and 1 case additionally underwent external expert consultation and comparative genomic hybridization. Patient 1 had axillary capsular blue nevi misread as nodal metastases, leading to unnecessary completion dissection. Patient 2 developed malignant blue nevus within a plaque-type blue nevus, with simultaneous benign capsular and vascular-adventitial blue nevus deposits. Patient 3 had amelanotic cellular blue nevus–like melanoma mimicking dermatofibroma, with negative comparative genomic hybridization despite a suspicious subcapsular sentinel-node focus. Integrated clinical, dermatopathological, immunomorphological, and molecular assessment is essential to avoid both under- and over-treatment.
Abstract: The advent of molecular techniques has significantly enhanced the classification of melanocytic and nonmelanocytic tumors with melanocytic differentiation. One notable development is the identification of tumors within the MITF pathway, including the rare MITF::CREM fusion–associated lesion. In this study, we present a case of a 16-year-old adolescent girl with a lesion located on the mid upper back. Histopathologic examination revealed a poorly circumscribed, hypercellular dermal-based neoplasm composed of epithelioid cells arranged in sheets and cords. Notably, clear cell changes were observed only after re-excision. Molecular analysis through genome and RNA sequencing confirmed the presence of an MITF::CREM fusion, marking this as a rare MITF-pathway fusion tumor. To date, such tumors have been infrequently reported in the literature. Accurate classification of melanocytic tumors is crucial for guiding management and predicting prognosis. This case highlights a rare subtype of clear cell tumor with melanocytic differentiation, underscoring the need for further case studies to better understand its potential behavior and clinical significance.
