In a series of 37 cases of calcifying epithelioma, three lesions showed microscopic melanization. In these three cases, melanin was present in shadow cells and stromal cells. One epithelioma was unusual because melanin was also present in dendritic melanocytes within masses of basophilic cells, and because the tumor showed gross pigmentation. The presence of dendritic melanocytes among the basophilic cells provided another similarity between calcifying epithelioma and hair bulbs.
Cazers JS, Okun MR, Pearson SH. Pigmented Calcifying EpitheliomaReview and Presentation of a Case With Unusual Features. Arch Dermatol. 1974;110(5):773-774. doi:10.1001/archderm.1974.01630110067019