DELETION OF CHROMOSOME ARM IP IN A MERKEL CELL-CARCINOMA (MCC)

A case of neuroendocrine skin carcinoma (Merkel cell carcinoma) with a deletion of the short arm of chromosome 1 (1p) as the sole chromosomal abnormality was examined. The tumor originated in the skin of the left knee of a 67-year-old man. Histopathologic study showed an undifferentiated small cell tumor which expressed neuron-specific enolase, chromogranin, and cytokeratin (CAM 5.2). Cytogenetic analysis of a lymph node metastasis from the groin showed a pseudodiploid cell population with a deletion of the short arm of chromosome 1 as the only abnormality: 46,XY,del(1)(p36.1). In situ hybridization with the D 1Z2 probe specific for the terminal band of I p confirmed the terminal deletion. This is the first case of Merkel cell carcinoma in which only one chromosomal abnormality has been observed. Loss of the terminal portion of Ip suggests that a tumor supressor gene on Ip plays a role in the pathogenesis of Merkel cell carcinoma. (C) 1994 Wiley-Liss, Inc.