Abstract

Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor. There have been only a few prior fine-needle aspiration (FNA) cytological reports. Recognition of this tumor is important because of its potential for metastasis despite its indolent nature and its deceptively bland cytologic appearance. A 60-year-old male presented with a slowly growing mass in the left calf detected 10 years ago. The patient underwent surgical excision. FNA cytology was performed directly on the mass. The smears showed low cellularity composed of hypercellular tissue fragments, hypocellular loose aggregates, and stripped nuclei. The cytoplasm was seen as either collagenous material or very thin fibrillary collagen strands. Tumor cells had spindle, ovoid, or irregular nuclei, fine chromatin, and small nucleoli. Focally slight degree of nuclear pleomorphism is noted. There were no mitotic figures. Blood vessels were frequently seen. Immunocytochemically, tumor cells were negative for S-100 protein, desmin, smooth muscle actin, and CD34. The diagnosis of LGFMS is rarely possible by cytology alone; however, LGFMS should be included in the differential diagnosis of spindle-cell tumors consisting of hypercellular and hypocellular components with some capillary-sized vessels arising in the deep soft tissue of the lower extremities, particularly the thigh. The immunocytochemical findings are of help in the differential diagnosis.

• Keywords: Soft tissue neoplasm;Low-grade fibromyxoid sarcoma;Aspiration biopsy