Fine-needle aspiration biopsy diagnosis of histiocyte-rich rhabdomyoblastic tumor (inflammatory leiomyosarcoma): A case report.

Histiocyte-rich rhabdomyoblastic tumor (HRRMT) is an exceedingly rare soft tissue tumor of primitive myogenic differentiation. We report herein a case involving the soft tissue in the left lateral peri-scapular region in a 68-year-old female with a 2-month history of a non-painful soft tissue mass. Ultrasound revealed a solid, ovoid subcutaneous mass lesion that lacked significant internal vascularity. Percutaneous fine-needle aspiration (FNA) biopsy with concomitant core needle biopsy was performed, and a diagnosis of HRRMT was rendered. Cytologic smears were hypercellular, composed of a mixture of foamy histiocytes and a variably cohesive population of epithelioid and plasmacytoid to vaguely spindled cells in cohesive clusters and singly dispersed. Histologic material showed sheets of epithelioid and plasmacytoid to spindled cells with admixed foamy histiocytes with distended, vacuolated cytoplasm. To our knowledge, this is the first reported example of HRRMT evaluated by FNA biopsy.