Pigmented pilomatricoma: an underrecognized variant.

The presence of melanin pigment and/or melanocytes in pilomatricoma has been rarely documented. In this study, we analyzed the incidence and clinicopathological features of pigmented pilomatricoma. Fifty-seven consecutive pilomatricoma cases from 53 Japanese patients were examined in this study. In fourteen cases (24.6%), pigmentation was observed in pilomatricoma. This variant equally affected in males and females, and the common locations were the upper arm and face. Proliferation of dendritic melanocytes was observed within basaloid cell nests in all cases, and melanin pigment was also present within the cytoplasm of the basaloid cells in 11 cases. Melanin pigment was also present in the shadow cells in 7 cases. The incidence of pigmented pilomatricoma as documented in previous reports is approximately 10%. However, our analysis revealed that pigmented pilomatricoma was found in 24.6% of Japanese cases of pilomatricoma, thus, this variant is not uncommon and may be under-recognized.