Immunohistochemical demonstration of ferritin in sweat gland and sweat gland neoplasms.

Using a rabbit anti-human liver ferritin antibody, we examined the binding patterns of this reagent in normal skin and observed a unique binding pattern limited to the outermost layer of the eccrine duct. Examination of a variety of sweat gland neoplasms revealed 2 distinct patterns. One was the binding of this antibody to the outermost layer of cells in the epithelial cords of syringoma, producing a characteristic ring when seen in cross-section. This pattern of binding did not occur in other neoplasms known to be related to the eccrine duct such as dermal duct tumor and eccrine poroma. Only sparse sporadic binding occurred in other eccrine and apocrine neoplasms. A second characteristic binding pattern, not related to that noted in syringoma and diffuse in pattern, was seen in acrospiroma and in a number of adnexal carcinomas. Diffuse ferritin expression has been described in malignant neoplasms in tissues other than skin. Diffuse ferritin staining of certain sweat gland neoplasms may be an indication of biologic activity and potential aggressivity of these neoplasms.