Primary neuroendocrine carcinoma of the skin. An analysis of 12 cases with microscopic and immunohistochemical study [IL CARCINOMA NEUROENDOCRINO PRIMITIVO DELLA CUTE. STUDIO MORFOLOGICO ED IMMUNOISTOCHIMICO DI DODICI CASI]

Background. Merkel cell carcinoma (MCC) is an unusual primary cutaneous tumor with an aggressive clinical course and a severe prognosis. Methods. Twelve patients with MCC were observed at The Department of Surgery and Oncology, University of Cagliari, between 1980 and 1994. In all cases diagnosis was made by histochemical (Grimelius) and immunohistochemical methods making use of APAAP method with monoclonal antibodies anti-Cytokeratins, anti-leucocyte common antigen (LCA), anti-S100 protein, anti-neuron-specific enolase (NSE) and anti-Chromogranine A. The difficulties of differential diagnosis with metastatic microcytoma which was made also from radiologic and strumental investigations are emphasized. Therapy consisted in a wide excision of the primary lesion, with margins of at least 2 centimeters, in 11 patients, associated with lymphoadenectomy in 2 cases and radio-and/or chemotherapy in 4 patients. Results. A relapse of the disease was observed in 5 of the 11 valuable patients, and heavily affected the survival (4 of the 5 patients died). Conclusions. Because of the high malignancy of the tumor, it is suggested that the best treatment, at present, is the wide local excision of the primary tumor accompanied by a radiation therapy in patients with high risk of relapse and with regional lymphoadenectomy in the case of tumors of considerable size. Chemotherapy is at present of very limited use, due to the age of the patients and its only temporary efficacy