Primary giant cell tumor of soft tissue. Report of a case with fine needle aspiration cytologic and histologic findings

BACKGROUND: So-called primary giant cell tumor of soft tissue of low malignant potential is the rare soft tissue analogue of giant cell tumor of bone, occurring primarily in superficial soft tissue. To our knowledge, the cytologic findings in bulky giant cell tumor of deep soft tissue were described only once, and no further report on the subcutaneous giant cell tumor could be retrieved from the literature. CASE: A 58-year-old woman presented with a well-demarcated, 1.5-cm-diameter dermal tumor. Fine needle aspiration smears contained numerous osteoclastlike giant cells and mononuclear cells showing bland and vesicular nuclei. A small fragment of branching vasculature and 1 mitosis were found. Those cytologic findings were enough to suggest a diagnosis of giant cell tumor of soft tissue, confirmed as a deep dermal giant cell on surgical resection. CONCLUSION: Primary giant cell tumor of soft tissue of low malignant potential should be considered in the differential diagnosis of bland-looking giant cell-rich lesions. Awareness of its existence and knowledge of its cytologic features are important for a correct preoperative cytologic diagnosis.