Secretory immunoglobulin A in sweat gland tumors.

The presence of immunoglobulin A (IgA) and secretory component (SC) was investigated in normal human skin and in cutaneous neoplasms including a variety of sweat gland tumors. Immunohistochemistry in normal sweat glands revealed the occurrence of secretory IgA (sIgA) as indicated by reactivity for IgA and SC in serial sections. The majority of 28 cases of sweat gland tumors could be demonstrated to retain their ability to produce IgA and SC. In normal as well as in neoplastic sweat glands heaviest staining for sIgA could be found in the lumina and at the surface of lining epithelia. This is comparable with the presence of sIgA in breast or intestinal neoplasms. In contrast other epidermal cysts or solid tumors were not labelled. In view of recent immunohistochemical studies the demonstration of IgA and SC may be of differentiating value in cutaneous glandular neoplasms.