鼠径部腫瘤を契機に発見されたMyxoid liposarcomaの1例

Abstract

40歳代男。右鼠径部腫瘤を自覚し、右鼠径ヘルニアの診断で根治術を受けるも腫瘤は消失せず、徐々に増大傾向となった。入院時、右鼠径部・陰嚢起始部に腫瘤を認め、腫瘍マーカーは全て正常範囲内であった。鼠径部エコー検査では内部血流に富むhigh echoicな腫瘤を認め、腫瘍と精索との関連は不明瞭であった。腹部CTでは右鼠径部に周囲との境界が明瞭で造影効果を認める腫瘤を認めた。単純MRIではT1強調画像で低信号、T2強調画像で高信号、T1強調画像で強い造影効果を認めるhypervascularなtumorと、その中心部に造影効果が不良なedemaを伴う部位を認めた。精索発生のliposarcomaを疑い、腰椎麻酔下に右精巣摘除術を行った。腫瘍は精索に沿う形で外精索筋膜外に存在し、癒着はみられず、腫瘍・精索・精巣を一塊として摘出した。腫瘍割面は灰白色ゼリー状で、組織学的には脂肪滴を有する核が辺縁に圧排された細胞、myxoid成分を含むゼリー状の細胞より構成され、間質内に小型血管の樹状走行を認めた。また、間質内にN/C比の高いround cellを認めたが細胞密度が低く、round cell成分を含まないtypeのmyxoid liposarcomaと診断された。偽被膜周囲に一部myxoid成分を含む娘結節を認めたため、術後鼠径部から右陰嚢にかけて補助放射線療法を行い、術後約半年間、転移・再発は認めていない。

We report a case of myxoid liposarcoma developed in the right inguinal region. A 45-year-old man visited our hospital with a chief complaint of painless right inguinal mass. He was diagnosed with right direct inguinal hernia for the first time and received a hernia repair. However, the size of the inguinal mass increased gradually after the operation. Then, the tumor was re-evaluated by imaging study such as ultrasonography, computed tomography and magnetic resonance imaging. A fatty mass 4.0 cm in diameter was demonstrated and the tumor was diagnosed as a liposarcoma preoperatively. In addition to the right high orchiectomy, surrounding fatty tissue was also removed at the time of the operation. Histological examination revealed a myxoid liposarcoma and the existence of several daughter regions outside the pseudo-capsule. Right spermatic cord and testis were intact. Postoperatively, he received 54 Gy dose of radiation therapy to right inguinal region for the prevention of the local recurrence of the disease.