粘液腫様成分を伴う高分化型脂肪肉腫とともに生じた横紋筋肉腫様の組織像を呈する縦隔脱分化型脂肪肉腫の1例

A case of dedifferentiated liposarcoma of the mediastinum presenting with rhabdomyosarcomalike histology, co‒existing with a well‒differentiated liposarcoma with myxoid components

一般に脱分化型脂肪肉腫は後腹膜を好発部位とし，脱分化成分は壊死・出血を伴う未分化多型肉腫様の組織像を呈することが多い。今回我々は，粘液腫様成分を伴う高分化型脂肪肉腫とともに生じ，まれとされる横紋筋肉腫様の組織像を有することで，3つの異なる腫瘍成分を有するかのような特異な画像所見を呈した縦隔発生の脱分化型脂肪肉腫の症例を経験した。そこで，画像・病理所見をふまえ，文献的考察を含めて報告する。

Generally, well-differentiated liposarcoma commonly arises in the retroperitoneum, and its dedifferentiated components are often characterized by histological features resembling undifferentiated pleomorphic sarcoma, which are commonly accompanied by necrosis and hemorrhage. We experienced a case of dedifferentiated liposarcoma arising from the mediastinum, exhibiting unique imaging features suggestive of having three different tumor components due to its rare rhabdomyosarcomalike histological features and having well-differentiated liposarcoma with myxoid components alongside. We report this case considering imaging and pathological findings along with a literature review for further discussion.