When is biopsy necessary in pelvic lipomatosis?

Pelvic lipomatosis has a classic roentgen triad which includes (1) pelvic radiolucency, (2) elevation of an intact rectosigmoid, and (3) elevation of the urinary bladder. This triad, in the absence of other abnormal clinical and roentgen findings, is pathognomonic of pelvic lipomatosis, and surgical biopsy is not necessary to confirm the diagnosis.