Melanocytic Matricoma: A report of 4 cases and review of the literature

Summary: Melanocytic matricoma is a rare, benign adnexal neoplasm with follicular (particularly matrical) differentiation. It typically presents in sun-damaged skin of the elderly. It is composed of the same histological elements as a pilomatricoma but with solid, anastomosing nodules of basaloid matrical or supramatrical cells and a variable number of interspersed melanocytes and degrees of pigmentation. There is some controversy regarding the classification of this entity in regard to separating it from pilomatricoma, and nomenclature of the pigmented component. We present four cases of this entity, and a review of the literature, with particular emphasis on the degree of atypia, necrosis, and mitotic activity seen under the microscope, all of which may be misinterpreted as signs of malignancy.