Malignant Extrarenal Rhabdoid Tumor of the Pelvic Paravertebral Region: Case Report

Malignant rhabdoid tumor (MRT) is a rare but distinctive neoplasm of unknown histogenesis, occurring primarily in children. It has a characteristic histologic pattern and aggressive clinical behavior, and was originally thought to be a malignant sarcomatous variant of Wilms tumor; numerous cases of MRT arising from extrarenal sites have, however, been reported. We describe the radiologic findings of two cases of malignant extrarenal rhabdoid tumor that arose in the pelvic paravertebral region of two children. Both were confirmed by surgical excision and pathologic examination.