A Case of Interdigitating Dendritic Cell Sarcoma of the Rectum

Masatsune Shibutani, Hitoshi Teraoka, Shigetomi Nakao, Yutaka Tamamori, Atsunori Nitta and Takaaki Chikugo*

Department of Surgery, Baba Memorial Hospital
Department of Pathology, Kinki University*

We report an extremely rare case of interdigitating dendritic cell sarcoma of the rectum. A 76-year-old man with dyschezia was found in digital examination to have an elastic hard tumor palpated about 2 cm proximal to the anal verge. Colonoscopy showed a semicircular tumor with a central ulcer similar to a submucosal tumor in the lower rectum. Biopsy, yielded no definite diagnosis, necessitating abdominoperineal resection of the rectum based on the suspicion of gastrointestinal stromal tumor with malignancy. Histological examination showed a diffuse proliferation of atypical cells with irregularly shaped nuclei. These cells had poor bondability and frequent atypical mitoses. Immunohistochemically, tumor cells expressed CD68, CD99, S-100, and vimentin, but were negative for CD1a, CD3, CD79a, CD117, fascin, smooth muscle actin, HLA-DR, and EBER-ISH. Electron microscopy showed no evidence of Birbeck granules. The definitive diagnosis was interdigitating dendritic cell sarcoma (IDCS). The patient received chemotherapy for the remnant lymph nodes swollen along with para-aortic region. As of 8months after the operation, decreasing tendency in the remnant lymph nodes has been observed. As for this disease, about 50cases are reported in the world in the past. Only one case of IDCS occurred to digestive organs has been reported, and this case is the first report that occurred to large intestine in Japan.

Key words
rectum, interdigitating dendritic cell sarcoma (IDCS)

Reprint requests
Masatsune Shibutani Department of Surgery, Baba Memorial Hospital
4-244 Hamadera-funao-machi higashi, Nishi-ku, Sakai, 592-8555 JAPAN

Accepted
January 27, 2010

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