Track: Case Reports

Abstract:

The rising complexity of skin neoplasms presents diagnostic challenges, particularly in rare entities with overlapping histologic features. We present a case of a 68-year-old female with a neoplasm initially suspected to be a squamomelanocytic tumor but ultimately favored to be a malignant melanocytic matricoma. Histological examination revealed a basaloid and squamous cell proliferation with an atypical melanocytic hyperplasia, shadow cells, and an infiltrative growth pattern. Immunohistochemical studies demonstrated diffuse β-catenin positivity, highlighting matrical differentiation, while molecular analysis identified a BRAF G464R mutation. Given the rarity and diagnostic ambiguity of these lesions, differentiation of melanocytic matricomas from malignant melanocytic matricoma remains challenging, particularly in the absence of definitive malignant criteria beyond metastasis. Further challenge exists between the differentiation of melanocytic matricomas from squamomelanocytic tumors due to histologic overlap. This case highlights the importance of thorough histopathologic evaluation, appropriate immunohistochemical studies, and molecular testing in distinguishing between rare cutaneous neoplasms to ensure accurate classification and optimal clinical management. Continued study of these entities is necessary to refine diagnostic criteria and establish appropriate treatment protocols.

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Shauna Wentzell