Case report:
A 68-year-old female with no medical history presented with a complaint of an abdominal painless mass. She has no associated urinary or digestive signs (as nausea, vomiting, dyspepsia or constipation). Physical examination showed a large hard non-mobile non-tender mass in the right hemi abdomen and extending from the subhepatic region down to the right pelvis. Laboratory findings and tumor markers were within the normal range. Computed tomography showed a voluminous retroperitoneal mass of 26 x 14 cm encasing entirely the right kidney (figure 1). It had a mixed content, mainly of fat density and some microcalcifications. The intestinal loops and other abdominal organs were displaced to the midline without any signs of tumoral invasion. The Ct-scan didn’t show any liver or pulmonary metastasis.
The patient underwent a midline laparotomy: a bulky, well-encapsulated mass was found arising from the right perinephric area and englobing entirely the right kidney. The tumor measuring 20 x 30 x 15 cm was totally excised en-bloc with the right kidney (figure 2). The radical nephrectomy was necessary to achieve clear macroscopic resection margins without any tumoral capsule break-in.
The patient had an uncomplicated postoperative course and was discharged to home on the 6th postoperative day.
Histological and immunohistochemistry analysis of the tumor revealed a dedifferentiated RLS with no evidence of tumor invasion of the kidney. Then, the patient had an adjuvant radiotherapy. After 18 months follow-up, the patient has no clinical or radiological signs of disease recurrence.