Immunohistochemical and electron microscopic studies of Langerhans cells in a case of multiple eccrine spiradenomas

Multiple eccrine spiradenomas are rare. In the present study, a detailed investigation of eccrine spiradenoma was performed, focusing in particular on the presence of Langerhans cells (LCs) in the tumor, and their immunohistochemical and ultrastructural characterization. The patient was a woman in her mid-forties who underwent resection of two tumors of the head that were 2.0 and 0.7 cm in size. They were diagnosed as eccrine spiradenoma and were composed of small and large tumor cells with a dense fibrous capsule in the dermis. Immunohistochemically, staining by antibodies to cytokeratins (AE1/AE3, CAM5.2) and CK 5/6 was diffusely positive in all tumor cells, although not in intermingled LCs, which harbored interdigitated nuclei. The cytoplasm of LCs was positive for S-100 protein and CD1a, and their nuclei were also occasionally positive for S-100 protein. Antibody to epithelial membrane antigen was positive for the surface of both intracytoplasmic and true glandular lumina. Fine structural examination revealed the presence of LCs among the tumor cells, extending fine irregular processes among the tumor cells. Birbeck granules were clearly demonstrated in the cytoplasm of LCs. Other fine structural findings included intracytoplasmic lumina with microvilli on their surfaces in some tumor cells. In these examinations of eccrine spiradenoma, LCs, approximately 15/HPF in the tumor, were distinctly detected even at light microscopic level as negative for various types of cytokeratin stains, although they were positive for S-100 protein and CD1a, whereas on ultrastructural examination Birbeck granules were demonstrated in their cytoplasm. Determination of the significance of these LCs in eccrine spiradenoma requires further investigation of a larger number of cases.