Solitary fibrous tumor in the pelvic space

A case of a solitary fibrous tumor (SFT) of the pelvic space in a 64-year-old man is reported herein. Computed tomography (CT) of the pelvis showed a large mass enhanced heterogeneously left paracentral and posterior to the bladder and intimately associated with prostate. The site of origin of the mass could not be defined on CT because margins blended with the bladder, prostate, and rectum. A tumorectomy was performed and has remained well with no evidence of recurrence during the last 3 months. The tumor was 12.5x9.5x8.3 cm in size, solid with a fibromuscular capsule, and gray-tan in color. Histologically, the neoplasms were well circumscribed and composed of short spindle cells arranged without an obvious pattern. Immunohistochemically, these cells were strongly positive for CD 34 and negative for S-100, alpha SMA, and AE1/AE3.