Diagnosis of malignant granular cell tumor by fine needle aspiration cytology:

Malignant granular cell tumors (GCT) are the rarest of all sarcomas, and the histologic differentiation from their benign counterpart may be extremely difficult or impossible unless metastatic disease is demonstrated. To our knowledge, this is the first report of a malignant GCT diagnosed by fine needle aspiration (FNA) cytology.

A 70-year-old, Caucasian female presented with a progressively enlarging left supraclavicular mass. FNA of the mass revealed a metastatic tumor cytologically consistent with GCT. With this diagnosis, a search for other metastatic sites was initiated. Computed tomography (CT) scan revealed several tumor nodules in the lungs and liver. CT-guided FNA and tru-cut needle biopsy of a liver mass confirmed the diagnosis of metastatic GCT. In searching for a primary site, the patient revealed a clinical history of having had a tumor removed from her back two months before; it was reported to be an atypical GCT. Comparison of the three tumors revealed similar histologic, cytologic and immunohistochemical features.

Evidence of mild to moderate cytologic atypia; increased mitotic activity; locally aggressive growth; increased proliferative activity as demonstrated by immunohistochemical evaluation of proliferation markers; and DNA ploidy analysis, as reported for this case, may be helpful in predicting malignant behavior of GCTs.