Melanocytic matricoma: A report of three cases, review of the literature, and suggestion of a new terminology.

Melanocytic matricoma is a rare, biphasic adnexal tumor. It typically presents as a pigmented papule on the sun-damaged skin of elderly patients. Histopathology shows a dermal nodule composed of basaloid cells, ghost cells, and deeply pigmented dendritic melanocytes. The basaloid cells are usually positive for β-catenin and these tumors show overlapping histopathological and molecular features with pilomatricoma. Here, we review the literature on melanocytic matricoma and present three new cases. We suggest different terminology to reflect the overlapping features with pilomatricoma that recognizes that melanocytic matricoma is likely to be a variant of pilomatricoma associated with melanocytic hyperplasia. Although melanocytic matricoma is usually considered benign, malignant transformation has been reported. This highlights the need for increased awareness of this entity.