Ductal carcinoma arising from a syringocystadenoma papilliferum in a nevus sebaceus of Jadassohn.

We present an example of ductal carcinoma connected to a syringocystadenoma papilliferum situated in a nevus sebaceus of Jadassohn on the scalp of a 22-year-old woman. The ductal carcinoma involved the entire thickness of the dermis and extended to the subcutaneous fat. Because syringocystadenoma papilliferum is considered a hamartoma with apocrine differentiation, the ductal carcinoma here described was interpreted as an apocrine ductal carcinoma. Syringocystadenocarcinoma papilliferum is an exceedingly rare neoplasm, most examples of which seem to have arisen in its benign counterpart, syringocystadenoma papilliferum. From a histopathologic point of view, syringocystadenocarcinoma papilliferum usually shows a papillary configuration similar to that of syringocystadenoma papilliferum. In contrast, the case here described a ductal carcinoma superficially connected to a syringocystadenoma papilliferum, but mostly composed of small ductal structures embedded in a desmoplastic stroma and involving the full thickness of the dermis. We review the literature about the malignant neoplasms arising in the nevus sebaceus of Jadassohn.