Features of benign granular cell tumor on fine needle aspiration

OBJECTIVE: To describe the cytomorphologic features of benign granular cell tumor (GCT) on fine needle aspiration (FNA) biopsy and discuss the differe ntial diagnosis, STUDY DESIGN: Were viewed three fine needle aspirates of surgically confirm ed benign GCT. Immunocytochemical staining for S-100 was performed an the a spirate smear in one case. RESULTS: Two GCT were thigh lesions, where lipoma and fibromatosis were the leading clinical diagnosis, and the third was a breast mass clinically sus pected to be a fibroadenoma. All FNA specimens were highly cellular and com posed of fairly uniform cells with eccentric, round-to-slightly oval nuclei and abundant,finely granular cytoplasm. The cells were fragile, with strip ped nuclei in a background of finely granular material. Occasional cells wi th nuclear pleomorphism and small-but-conspicuous nucleoli were identified. There was no evidence of necrosis or mitotic activity. Rare intranuclear c ytoplasmic inclusions were identified in two cases. The granular cells were immunoreactive for S-100 in the case studied. CONCLUSION: Benign GCT has a distinctive cytomorphologic appearance that pe rmits its diagnosis on ENA. High cellularity, occasional cells with nuclear pleomorphism and prominent nucleoli are features that can be present in be nign GCT, Mitotic figures and necrosis should be identified before a diagno sis of malignancy is rendered.