[Clear-cell eccrine carcinoma of the plantar region. Follow-up of a case using histochemistry, immunohistochemistry, and flow cytometry].

Clear cell eccrine carcinomas of the skin are rare and have been reported with several names. Of the 47 cases found in the literature, only one had the lesion in the sole. The present case is a 38 year old woman with an 18 year history of a 3.2 cm lesion in the lateral portion of the sole in the right foot. The patient developed inguinal metastases four and five months after the plantar resection, and suffered a local recurrence on two occasions. The histopathologic analysis of the sole lesion showed a neoplasm with more than 80% of clear cells, and less clear cells in the metastatic and recurrent lesions. Clear cells showed diffuse positivity to PAS with diastase lability. PAS reactivity was related to the presence of clear cells. Focal reactivity of mucin and colloidal iron in sebaceous-like cells and tubular structures was seen. Also, we found diffuse cytoplasmic and membrane surface positivity of epithelial membrane antigen in the clear cells, and focal in poroid and sebaceous cells and in tubular structures. The carcinoembryonic antigen showed a focal positivity in poroid and sebaceous cells and in tubular structures. We also identified focal positivity of S-100 protein in the sebaceous-like cells. Cytophotometric measurement of the nuclear DNA showed euploid cells in the primary and metastatic lesions. We conclude that clear cell eccrine carcinomas comprise a heterogeneous group of lesions with variable biological behavior, but with morphological, histochemical and immunohistochemical markers useful in their diagnosis.