肝過形成性病変内に生じた胎児型肝芽腫の1例

A case of fetal hepatoblastoma within a hepatic hyperplastic lesion

肝芽腫は肝前駆細胞由来の胎児性悪性腫瘍で，5歳未満の小児肝悪性腫瘍の約80～90％を占める^1）2）。我が国での2011～2017年の全国登録調査において肝芽腫は245例とまれな疾患であるが，近年増加傾向である^3）。肝芽腫は診断時にはすでに大型腫瘍を呈し，腹部膨満や腹部腫瘤などを契機に超音波検査で発見されることが多い^4）5）。

We report an extremely rare case of a 3-year-old boy with a fetal hepatoblastoma that developed within a presumed hyperplastic lesion. The lesion had been first detected by ultrasound two years before and shown slightly hypointense on the hepatobiliary phase and penetrating vessels on gadoxetic acid-enhanced MRI. Two years later, a multinodular mass appeared in the same region, exhibiting intratumoral fat, arterial hyperenhancement, washout, and markedly hypointense on the hepatobiliary phase, with elevation of alphafetoprotein. Histopathological examination confirmed a fetal hepatoblastoma with surrounding hyperplastic changes, suggesting that the hepatoblastoma may have arisen from the pre-existing hyperplastic lesion.