Unexpected Massive Hemorrhage During Incision and Drainage of a Presumed Perianal Abscess: A Case of Pelvic Chondrosarcoma.

Chondrosarcoma is a malignant cartilaginous neoplasm that commonly affects the pelvis. Due to its indolent growth pattern and deep anatomical location, pelvic disease may remain undetected until the lesion reaches a considerable size. In the present case, a 62-year-old male presented with a presumed perianal abscess and underwent incision and drainage, leading to unexpected massive hemorrhage intraoperatively. A subsequent contrast-enhanced CT scan demonstrated a large destructive pelvic lesion containing chondroid-type calcifications and prominent internal vascular channels. This case highlights the importance of radiological evaluation when clinical findings are atypical or inconclusive.