Retroperitoneal desmoid tumor

Case contributed by Michael P Hartung
Diagnosis certain


Left hip pain.

Patient Data

Age: 30 years
Gender: Female

Very large extraperitoneal left pelvic mass displacing and in places indistinguishable from the iliopsoas and iliacus muscles, anteriorly displacing vasculature. 


Large enhancing, T2-hyperintense left retroperitoneal mass encases the lumbosacral plexus and sciatic nerves. Displaces and likely invades portions of the iliopsoas and iliacus muscles. 

Case Discussion

Ultrasound guided biopsy confirmed desmoid-type fibromatosis. Most cases of desmoid are intraperitoneal or abdominal wall masses, and an extra/retroperitoneal pelvic mass encasing nerves is a less common presentation.

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