Characterization of cell lines established from Merkel-cell ("small-cell") carcinoma of the skin.

Six cell lines have been established from different biopsies of the rare small-cell skin cancer of neuro-endocrine origin known as Merkel-cell carcinoma (MCC). These were established from metastatic lesions and have now been in culture for periods varying from 1 to 3 years. All lines grow as suspension cultures and exhibit typical MCC cytological features of small round cells with little cytoplasm, round nuclei and tight junctions. There was variation in the number and size of nucleoli and dense-core granules. We present details of their immunohistochemistry and growth characteristics in culture. The latter were similar to small-cell lung-cancer (SCLC) lines and can be subdivided, by their appearance, into type I, type II and type III in the same way as SCLC lines. This classification may be of significance for the prognosis and management of MCC.