FINE-NEEDLE ASPIRATION OF MERKEL CELL-CARCINOMA OF THE SKIN WITH CYTOMORPHOLOGY AND IMMUNOCYTOCHEMICAL CORRELATION

Merkel cell carcinoma (MCC) of the skin is a rare, primary malignant s kin neoplasm which can present as a cutaneous nodule. These neoplasms are seen primarily in the elderly and located in the head and neck are a or extremities. Twenty-nine aspirates from primary and metastatic le sions obtained by percutaneous fine-needle aspiration in 19 patients h ave been studied. The cytomorphologic features, clinical information, and immunocytochemical (ICC) findings are detailed. Aspirate smears de monstrated small-to-intermediate-sized cells with a loosely cohesive p attern . Nuclei were round with finely granular chromatin and multiple , small nucleoli. Cells possessed a thin tint of cytoplasm, and infreq uent pseudorosette formulations were noted in cell groups. ICC results were universally positive for cytokeratin, which showed a para-nuclea r ''dot like'' pattern. Neuron-specific enolase, epithelial membrane a ntigen, and S-100 protein were positive in varying degrees. Leukocyte common antigen,vas universally negative. The diagnosis of MCC of the s kin by FNA call be made by applying cytologic features in addition to ancillary studies and clinical information. (C) 1998 Wiley-Liss, Inc.