Low-grade fibromyxoid sarcoma metastatic to the prostate

Spindle cell tumors of the prostate are rare and mostly primary. We report a case of retroperitoneal sarcoma, which is a low-grade fibromyxoid sarcoma involving the prostate secondarily by metastasis. The patient was a 44-year-old man who presented with progressing abdominal pain. Computed tomography showed a large retroperitoneal mass. The patient underwent surgical resection. Intraoperatively, a second smaller mass was identified in the pelvis and was left untouched. The resected retroperitoneal specimen and prostate transrectal needle biopsies taken afterward showed the same mesenchymal tumor. Radical cystoprostatectomy was performed. Metatatic tumor involving the prostate, bilateral seminal vesicles, and base of the urinary bladder was found. Microscopic examination revealed typical histomorphologic features of low-grade fibromyxoid sarcoma. The patient is without evidence of disease 3 years postoperatively. This case is the first documentation of metastatic sarcoma to the prostate and expands the list of malignant mesenchymal neoplasms that may involve this organ.