フェレットにおける横紋筋肉腫の1例 Rhabdomyosarcoma in a Ferret (Mustela putorius furo)

5歳去勢済み雄フェレットの右胸壁皮下に腫瘤を認めた。組織学的には好酸性の豊富な細胞質と円形〜卵円形,時に奇怪な核を有す大型で多形性の強い腫瘍細胞束が錯綜しつつ,浸潤性に増殖。右腋窩リンパ節に転移を認めた。免疫染色でビメンチン,デスミン及びミオグロビン強陽性,骨格筋クレアチニンホスホキナーゼは細胞質内に果粒状に陽性。超微形態的に細胞質内に未熟な筋原線維が見られた。この腫瘍を横紋筋肉腫と診断した。

A 5-year-old spayed male ferret showed a subcutaneous mass in the right lateral thoracic wall. Microscopic examination revealed that the neoplasm had proliferated in the subcutis with infiltration into the surrounding tissues. A packed bundle of large polymorphic neoplastic cells, containing abundant eosinophilic cytoplasm and a round to ovoid, occasionally bizarre nucleus, were arranged interwoven. The neoplasm had metastasized to the right axillary lymph node. The neoplastic cells were intensively positive for vimentin, desmin and myoglobin. Skeletal muscle type creatine phosphokinase-positive granules were detected in the cytoplasm. Ultrastructurally, various amounts of disorganized myofibrils with focal density resembling the Z-band were shown in the cytoplasm of the neoplastic cells. The neoplasia was diagnosed as rhabdomyosarcoma.