食道胃接合部にみられた悪性神経鞘腫の1例

Malignant Schwannoma at the Esophago-Gastric Junction, Report of a Case

　食道胃接合部の粘膜下腫瘍の報告には平滑筋腫，平滑筋肉腫などの筋原性腫瘍が多くみられ，次いで神経性腫瘍が目立つが，いずれにしても，これらの外科処置に当たっては占居部位ならびに良悪性の術前診断が極めて重要である．部位的にはX線診断に多くの期待が求められることが多い．本症例はX線・内視鏡検査ともに噴門部の胃内発育型粘膜下腫瘍像を呈したが，大部分が食道粘膜で覆われており，組織学的にも多くの論議がなされた孤立性食道胃接合部悪性神経鞘腫であった．

　Leiomyoma is most frequently found in non-epithelial tumors of the esophago-gastric junction, followed by neurofibroma and schwannoma of neurogenic tumors. A case of malignant schwannoma in a 52-year-old woman which developed on the esophago-gastric junction without any clinical evidence, and was detected accidentally through an examination.

　The café-au-lait spot observed in Recklinghausen's disease was not seen. The tumor existed on the esophago-gastric junction, and was 4.5×3.0×2.0 cm in size. It was exposed in the lumen of the stomach and had a daughter nodule of 1.0×1.0 cm in size on the top of the major tumor.

　The tumor with the fibrous capsule grew, depressing the surrounding tissue in the submucosal layer. Histologically, it had both myogenic and neurogenic characteristics, and showed severe collagene and hyaline degeneration. Therefore, it was very difficult to establish a histological diagnosis. Since the tumor showed a histological whirl formation, a reticuline fiber appearance and a morphological change of the nuclei by means of silver reticuline staining, it was diagnosed as schwannoma with neurogenic characteristics.

　Though there was no typical mitosis in the daughter nodule, schwannoma showed partial malignant transformation because of the appearance of abundant atypical cells.