Abstract: Atypical Melanocytic Matricoma: A Case Report.
Melanocytic matricoma is a rare biphasic cutaneous adnexal neoplasm composed of matrical epithelial cells admixed with dendritic melanocytes. First described in 1999, fewer than several dozen cases have been reported in the literature. These lesions most commonly arise on chronically sun-exposed skin of older adults and typically present as small, pigmented papules or nodules that may clinically mimic melanoma. Histopathologic evaluation is required for diagnosis and characteristically demonstrates matrical differentiation with shadow cell formation and admixed melanocytes. Atypical variants with increased cytologic atypia or mitotic activity can further complicate distinction from malignant melanocytic proliferations.
An 83-year-old Caucasian male presented for a general skin evaluation with concerns of an irregular papule on the dorsal hand that had been present for over one year. Physical examination revealed a 7 mm verrucous crusted papule. A shave biopsy demonstrated a dermal proliferation of basaloid matrical cells with scattered shadow cells and numerous pigmented dendritic melanocytes. Cytologic atypia and increased mitotic activity were noted. Immunohistochemical staining supported a biphasic epithelial and melanocytic population and helped exclude melanoma. These findings were most consistent with atypical melanocytic matricoma. The lesion was subsequently treated with complete surgical excision, and histopathology confirmed clear margins without residual tumor.
This case highlights the diagnostic challenges posed by atypical melanocytic matricoma, particularly its clinical and histologic overlap with melanoma and other pigmented adnexal tumors. Recognition of characteristic matrical differentiation and the use of immunohistochemical analysis are essential for accurate diagnosis. Complete surgical excision with negative margins appears to be curative in most cases, though the limited number of reported cases makes prognostic assessment difficult. This report adds to the growing literature describing the clinical and histopathologic features of this uncommon neoplasm and emphasizes the importance of clinicopathologic correlation in guiding management.
An 83-year-old Caucasian male presented for a general skin evaluation with concerns of an irregular papule on the dorsal hand that had been present for over one year. Physical examination revealed a 7 mm verrucous crusted papule. A shave biopsy demonstrated a dermal proliferation of basaloid matrical cells with scattered shadow cells and numerous pigmented dendritic melanocytes. Cytologic atypia and increased mitotic activity were noted. Immunohistochemical staining supported a biphasic epithelial and melanocytic population and helped exclude melanoma. These findings were most consistent with atypical melanocytic matricoma. The lesion was subsequently treated with complete surgical excision, and histopathology confirmed clear margins without residual tumor.
This case highlights the diagnostic challenges posed by atypical melanocytic matricoma, particularly its clinical and histologic overlap with melanoma and other pigmented adnexal tumors. Recognition of characteristic matrical differentiation and the use of immunohistochemical analysis are essential for accurate diagnosis. Complete surgical excision with negative margins appears to be curative in most cases, though the limited number of reported cases makes prognostic assessment difficult. This report adds to the growing literature describing the clinical and histopathologic features of this uncommon neoplasm and emphasizes the importance of clinicopathologic correlation in guiding management.