A Case of Lower Rectal Gastrointestinal Stromal Tumor Underwent Operation with Anus Preservation after Neoadjuvant Chemotherapy

Shiho Natori, Hidenobu Masui, Ryo Takagawa, Ikuko Ota, Yasuyuki Kojima, Youhei Hamaguchi, Tadao Fukushima, Masatoshi Mogaki, Kaoru Nagahori and Yukio Tsuura*

Department of Surgery and Department of Pathology*, Yokosuka Kyosai Hospital

A 30-year-old woman was referred to our surgical department because of a rectal tumor found by her gynecologist during delivery. Digital examination showed an unmovable, 4-cm elastic-hard tumor in the posterior to right wall of the lower rectum, just above the dentate line. Colono-fiberscopic findings showed an elevated submucosal tumor that had partially extended into the anal canal at the tumor's deepest region. A CT scan revealed a solid 5-cm tumor involving the anal sphincter muscle. A core needle biopsy was performed under spinal anesthesia because the conventional colono-fiberscopic biopsy was unsuccessful. A histological diagnosis of the biopsy specimen indicated a gastrointestinal stromal tumor (GIST). Microscopic examination demonstrated spindle-shaped tumor cells with frequent mitotic figures and immunohistochemical positivity for c-kit and CD-34. The patient was treated with imatinib mesylate at a daily dose of 400 mg. One month later, the size of the tumor had decreased to a diameter of 2.5-cm. Trans-anal local excision was performed, with anus sphincter preservation. This case showed that imatinib chemotherapy was significantly effective against GIST, making an abdominoperineal resection unnecessary. Although the primary treatment for GIST remains surgical resection, the present case suggests that imatinib may be useful as a neoadjuvant chemotherapy.

Key words
gastrointestinal stromal tumor, imatinib mesylate, neoadjuvant chemotherapy

Reprint requests
Shiho Natori Department of Surgery, Yokosuka Kyosai Hospital
1-16 Yonegahamadori, Yokosuka, 238-0011 JAPAN

Accepted
July 26, 2006

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