Proliferation of eccrine sweat ducts associated with alopecia areata.

Proliferation of sweat ducts has been described as a reactive process in a variety of benign and malignant neoplasms and inflammatory conditions in the skin, including scarring alopecia. However, to our knowledge this phenomenon has not been observed in non-scarring alopecia. The following case documents such a proliferation arising in an alopecia consistent with alopecia areata. An 83-year-old female developed progressive, fairly well circumscribed patches of alopecia over a 2-3 year period. Unequivocal scarring was not present. Histopathological examination revealed non-scarring alopecia with miniaturized and telogen follicles and a proliferation of eccrine ductal structures in the reticular dermis. These ductal structures varied in size and degree of cystic dilatation and resembled a primary eccrine neoplasm, such as syringoma. Only minimal focal fibrosis was observed in association with the eccrine proliferation. In summary, this case indicates that eccrine sweat duct proliferation may occur in non-scarring alopecia and must be differentiated from a primary eccrine neoplasm.