Chondroid syringoma associated with hidrocystoma-like changes. Possible differentiation into eccrine gland. A histologic, immunohistochemical and electron microscopic study.

A case of chondroid syringoma associated with hidrocystoma-like changes was investigated by histology, immunohistochemistry and electron microscopy. Chondroid syringoma was histologically compatible with apocrine mixed tumor, and hidrocystoma-like changes did not fulfill diagnostic criteria of either eccrine hidrocystoma or apocrine hidrocystoma. However, epithelial cellular elements composing both chondroid syringoma and hidrocystoma-like changes suggested, immunohistochemically and electron microscopically, differentiation into eccrine gland. The lesions of both had an apparent transition of ductal structures of chondroid syringoma into hidrocystoma-like changes. Therefore, chondroid syringoma and hidrocystoma-like changes in this case may be organized as a peculiar type of cutaneous appendage tumor differentiating toward eccrine gland.