[Liposarcoma of the perirenal cell].

Objectives: To show the imaging tests characteristics and differential diagnosis of masses located within the retroperitoneal perirenal area.

Methods: Diagnostic imaging tests (KUB x-ray, ultrasound, helical CT scan with IV contrast) and follow-up in one case of perirenal cell liposarcoma.

Results: The study of the surgical specimen after renal tumorectomy in a patient with a solitary kidney resulted in the present diagnosis.

Conclusions: Liposarcoma is a malignant neoplasia derived from fatty tissue. Approximately 13% are located in the retroperitoneal area, and less than 1/3 arise from perinephric fat. We report one case of liposarcoma located in the perirenal cell as an incidental finding during contralateral psoas muscle abscess follow-up in a patient with a solitary kidney after surgery for xanthogranulomatous pyelonephritis. Successive controls during the last year allowed us to evaluate the evolution of this lesion's.