Cytomorphologic features of merkel cell carcinoma in fine needle aspiration biopsies - A study of two atypical cases

OBJECTIVE: To report atypical cytomorphologic features in fine needle aspir ation biopsies (FNABs) from two cases of Merkel cell carcinoma (MCC), a pri mary neuroendocrine neoplasm of skin. STUDY DESIGN: Retrospective review of FNABs with histologic correlation fro nt six patients with MCC and a report of findings from two whose smears sho wed atypical features. RESULTS: Typically the aspirates produce highly cellular smears of loosely clustered and individual, relatively monomorphic, small tumor cells with ro und to oval, regularly contoured nuclei. In two of our cases, the tumor cel l nuclei exhibited a spectrum of pleomorphism ranging from moderately compl ex nuclear membranes with cleaves, indentations and protrusions in one case to large, markedly bizarre, convoluted it nuclei and multi-nucleate tumor cells in the extreme case. Both cases were Finally neoplasms, the diagnosis ions based on clinical, histochemical and immunohistochemical data. Additi onally, electron microscopy tons performed on the tumor with bizarre nuclei and demonstrated rare, dense core neurosecretory granules and paranuclear bundles of intermediate filaments.