眼球内容除去術後に発生した平滑筋肉腫の1例

A case of leiomyosarcoma following exenteration of the eyeglobe

　78歳女性の平滑筋肉腫の1例につき報告する。約20年前，両絶対緑内障のため眼球内容除去術の既往がある。今回，前方に突出した眼窩腫瘍を認め，組織診にて平滑筋肉腫を疑われたため，眼窩内容除去術を施行された。その病理組織所見では，好酸性細胞質を有し核の大小不同を持つ紡錘形細胞が束状に配列していた。免疫染色では抗平滑筋actin filament抗体陽性であった。電顕所見では細胞質内のmyofilamentやdense patchなど平滑筋由来の細胞の特徴を有し，不連続な基底膜やpinocytotic vesi—clesに乏しいことなどは悪性腫瘍細胞の所見とみなされた。本腫瘍は下眼瞼原発と推測され，眼球内容除去術との関連はないものと考えられた。

A 78-year-old woman presented with an enlarging tumor in the right orbit. She had undergone bilateral exenteration of the eyeglobe for absolute glaucoma 20 years before. The tumor was connected with the lower eyelid. Biopsy showed suspected leiomyosarcoma or malignant schwannoma, leading to exentera-tion of the right orbit. The tumor had no relation to the residual eyeglobe and seemed to have originated from the lower eyelid. Histologically, the tumor was composed of interlacing bundles of spindle-shaped cells. The cells had acidophilic cytoplasm and blunt-ended nuclei. Nuclear pleomorphism and mitoses were present. Immunohistopathologically, the tumor cells stained with anti smooth muscle actin antibody. Electron microscopy showed numerous cytoplasmic myofilaments and dense patches, discontinuous basal lamina and very few pinocytotic vesicles. The histopathological diagnosis was leiomyosarcoma.