[Sclerosing epithelial hamartoma: variant of trichoepithelioma. Three cases (author's transl)].

The sclerosing epithelial hamartoma is a variant of suborganoid hamartoma with pilar differenciation, which was set apart as a distinct entity by MacDonald, Wilson Jones and Marks in 1977. It is similar to the disease formerly described under the title "solitary trichoepithelioma". The clinical and histological features in the three cases of sclerosing epithelial hamartoma that we are reporting differed from those of multiple trichoepithelioma, from which this hamartoma must be separated nosologically. We want to emphasize the quite unusual histological appearance of our third case. The keratinizing cystic structures were quire voluminous and superficial, and there were very few epithelial strands, th histological picture thus being very misleading. We have observed a prominent associated sebaceous hyperplasia architecturally atypical which allowed this sebaceous hyperplasia to be compared to sebaceous epithelioma. Moreover, numerous cholesterol crystals were present in the keratinizing cystic structures. These crystals appeared to be breaking the epithelium of the cyst wall, which resulted in foreign body epitheloid granuloma formation. Nosologically, the sclerosing epithelial hamartoma stands between trichofolliculoma and multiple trichoepithelioma.