Abstract
A forty-five-year-old man with organoid nevus involving the scalp had three different adnexal tumors within the lesion, for a few years. Histologically, they were confirmed as basal cell epithelioma, syringocystadenoma papilliferum, and sweat apparatus-derived benign tumor. The last tumor microscopically showed numerous dilated channels lined with a double layer of epithelial cells that form papillations projecting into the lumen. There was no evidence of decapitation and some lumina were filled with amorphous eosinophilic material. This routine finding prompted us to carry out immunohistochemical investigations with eccrine sweat gland-associated antibodies. SKH1 and anti-CEA antibodies stained only the inner layer of the dilated channels and EKH4 stained only the flattened outer layer of the cells, thereby suggesting these dilated channels are derived from the eccrine sweat gland. Our final diagnostic term of this tumor was eccrine papillary adenoma. Statistically, the 28 cases of organoid nevus that have been reported developed more than two secondary arising tumors within the lesion, and only 7 cases had more than three distinct tumors, in the Japanese literature from 1965 to 1987. Our statistical survey showed few cases of organoid nevus in association with eccrine sweat apparatus derived tumors. Our present report seems to be the first of an association of organoid nevus with eccrine papillary adenoma.
