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

Abstract

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.

Melanocytic matricoma: Two cases of an uncommon entity

“…Melanocytic matricoma typically presents as a small darkly pigmented papule on sun-damaged skin of elderly male patients. 3 Presentation on females appears to be significantly less common. 4 The clinical differential diagnosis includes pigmented pilomatricoma, basal cell carcinoma with matrical differentiation, pigmented trichoblastoma.…”

“…These cases contribute to the literature as they reinforce the clinical presentation of melanocytic matricoma, with both cases presenting as small, pigmented papules on sun damaged skin of elderly men. 3 …”

Melanocytic Matricoma: A Potential Mimic of Malignant Melanoma

“…In the existing literature, there has been some controversy regarding the proper characterization of this tumor. Some have suggested that melanocytic matricomas are either a subtype of pilomatricoma or exist on a spectrum, including pilomatricomas [1,5].…”

“…The tumor contains basaloid cells (round nuclei, stippled chromatin, prominent nucleoli) that transition into shadow (ghost) cells (anucleate, eosinophilic, keratinized cytoplasm) in a manner that can be either abrupt or gradual [1]. The tumor also contains melanocytes, which are usually intermixed among the other components of the tumor [1].…”

“…Melanocytic matricoma is an extremely rare, biphasic tumor that presents most commonly as a pigmented papule on the sun-damaged skin of older patients [ 1 ]. It was first described by Carlson et al in 1999 as a biphasic tumor harboring both melanocytic and epithelial components [ 2 ].…”