[Anaplastic large cell lymphoma and keratoacanthoma].

In CD30 positive lymphoproliferative disorders, e.g. anaplastic large cell lymphoma (ALCL) and lymphomatoid papulosis (LyP), pseudoepitheliomatous hyperplasia may occur in up to 50 percent of the cases. Epithelial tumors are rarely associated with ALCL or LyP, but the presence of single CD30 positive cells among the infiltrate accompanying epithelial tumors such as basal cell carcinomas and keratoacanthomas is well known. A 66-year-old man developed within a plaque of ALCL a rapidly growing epithelial tumor which we classified according to the clinical and histological features as keratoacanthoma. This case underlines the intimate interaction between CD30 positive lymphocytes and epithelial cells.