特異な形態を呈した食道巨大脂肪肉腫の1例

Giant Esophageal Liposarcoma Presenting in a Peculiar Form, Report of a Case

要旨●患者は60歳代，男性．4か月前より増悪する嚥下困難を主訴に当院を受診．EGDにて食道入口部を基部とした有茎性の巨大な粘膜下腫を認め，茎部で3つ頭に枝分かれした形態を呈していた．生検では診断に至らず，頸部切開アプローチによる食道腫瘍切除術を施行．腫瘍は線維性間質に富む脂肪様組織を呈しており，免疫組織化学染色で脂肪細胞，間葉系細胞のいずれも，MDM2がfocalに陽性，p16がびまん性に陽性を示した．FISHにてMDM2遺伝子増幅を検出し，高分化型脂肪肉腫と診断した．切除断端は免疫組織化学染色にてMDM2，p16陽性細胞を認めず，断端陰性と判断．術後3年後も再発なく経過している．

　A 60-year-old man presented with progressive dysphagia over four months and underwent an upper gastrointestinal endoscopy. Esophagogastroduodenoscopy revealed a large, pedunculated submucosal tumor originating near the esophageal entrance. The tumor exhibited a unique morphology, branching into three distinct heads at its stem. Initial biopsy results were inconclusive, prompting esophageal tumor resection via a cervical approach. Immunohistochemical analysis demonstrated focal MDM2 positivity and diffuse p16 positivity in both adipocytes and mesenchymal cells. FISH（Fluorescence in situ hybridization）confirmed MDM2 gene amplification, leading to a diagnosis of well-differentiated liposarcoma. Histological examination of the resection margins revealed atypical adipocytes and mesenchymal cells. However, immunohistochemical staining showed no evidence of MDM2- or p16-positive cells at the margins, confirming negative surgical margins. The patient showed no evidence of recurrence during three years of postoperative follow-up.