Malignant Mesenchymoma of the Retroperitoneum Involving Cecal Carcinoma: A Case Report

Hiroshi Itoh, Naotaka Kadoya, Katsunobu Oyama, Masafumi Inokuchi, Wataru Fukushima, Hirotaka Masutani, Hisashi Hirosawa, Ryouhei Izumi, Teisuke Hirono and Katsuhiko Saitoh^*

Department of Surgery and Pathology^*, Toyama City Hospital

A 78-year-old woman who complained of left lower abdominal pain was admitted to our hospital. Physical examination showed a surgical operation scar for left nephrectomy which had been performed for a retroperitoneal xanthogranuloma 12 years before, and revealed an elastic hard mass, approximately 10 cm in diameter, in the left lower abdominal region. Biochemical investigations showed elevations of carcinoembryonic antigen and carbohydrate antigen 19-9. Computed tomography revealed a retroperitoneal tumor around the descending colon containing focal calcification with abundant fat. Barium enema examination demonstrated the oppression of the descending colon to the inner part by the retroperitoneal tumor, and a cecal tumor. Under a diagnosis of recurrent xanthogranuloma of the retroperitoneal region and cecal carcinoma, left colectomy including the retroperitoneal tumor was performed because of an intraoperative diagnosis of myxoid sarcoma, therefore, ileocecal resection with a D2 lymphadenectomy were also performed. Macroscopic findings of the resected specimen showed normal mucosa of the descending colon, and the tumor from the subserosa to retroperitoneum, which was composed of tan-yellow or gray-white various fibrous or myxomatous tumors with focal osteogenic change. Histologically, the tumor consisted of chondrosarcoma, osteosarcoma, leiomyosarcoma, liposarcoma, which was compatible with malignant mesenchymoma. Histopathological findings of cecal carcinoma were as follows: macroscopically type 2, well differentiated adenocarcinoma, ss, ly₂, v₀, n₁ (+). As far as the Japanese literature is concerned, our case seems to be the 22 nd case of retroperitoneal malignant mesenchymoma, and the first case that describes the malignant mesenchymoma involving carcinoma. Here, we report a rare case of interest in histogenesis with a review of the literature.

Key words
malignant mesenchymoma, retroperitoneal tumor, xanthogranuloma

Reprint requests
Hiroshi Itoh Department of Surgery, Toyama City Hospital 2-1 Imaizumihokubu, Toyama, 939-8511 JAPAN

Accepted
September 22, 1999

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