A case of syringocystadenocarcinoma papilliferum in situ occurring partially in syringocystadenoma papilliferum.

We report a case of syringocystadenocarcinoma papilliferum in situ associated with syringocystadenoma papilliferum. The patient was a 64-year-old man with a red tumor that arose on top of his head two years before he consulted our department. The histological findings revealed a papillomatous growth on the epidermis forming several invaginations. Numerous papillary projections, lined by a two-layered epithelium with a benign appearance and decapitations on the luminal surface of the cells, extended into the lumens of the invaginations. Some projections showed a disorderly arrangement of multilayered cells with atypical nuclei. No differences between findings in the syringocystadenocarcinoma papilliferum in situ and those in the syringocystadenoma papilliferum were observed histochemically (PAS) or immunohistochemically (cytokeratin, CEA, CA 19-9, S-100, gross cystic disease fluid protein, lysozyme and Leu M1).