特異な形態を示した横行結腸神経鞘腫の1例

Pedunculated Type of Benign Schwannoma in the Transverse Colon, Report of a Case

要旨　患者は44歳，男性．下腹部痛を主訴に来院した．注腸X線検査では横行結腸に有茎性の分葉状隆起性病変を認め，大腸内視鏡検査では腫瘍表面は正常粘膜で覆われていたが，一部に浅い地図状の不整形潰瘍を認めた．生検で神経鞘腫を疑い，横行結腸切除術を施行した．切除標本は病理組織学的に紡錘型細胞の柵状配列と好酸球，肥満細胞の浸潤を認め，免疫組織染色ではS-100蛋白が陽性を示した．以上から神経鞘腫と診断した．大腸神経鞘腫は比較的少なく，なかでも，結腸に発生した症例はまれである．また，形態的に有茎性の分葉状隆起を示した報告は本邦では自験例が初めてであり，貴重な症例と考え，報告した．

　A 44-year-old man was admitted to our hospital for more detailed examination of his lower abdominal pain. Barium enema and colonoscopic examination demonstrated a pedunculated lobular polypoid lesion with partial ulcerations in the transverse colon. The surface of the lesion except for the ulcerated area was covered with almost normal mucosa. Microscopic examination of the biopsy specimen suggested schwannoma. Transverse colectomy was performed. The resected specimen showed a lobulated polypoid lesion with a long stalk and a smooth surface except for the ulcerated area. Histological examination confirmed a benign schwannoma originating from the submucosal layer. It was composed of spindle cells with a palisading arrangement, and was infiltrated with eosinophiles and mast cells. It was strongly immunohistochemically stained by S-100 protein and Vimentin antibodies, but not by muscle specific actin and desmin antibodies. Schwannoma of the large intestine, particularly the pedunculated type, is a rare tumor, and this is the first case in Japan.