[Hepatic mesenchimal hamartoma in neonates]

To approach the diagnosis and management of two different features of hepatic mesenchymal hamartoma (HMH) in the neonate.

Report of two cases of HMH in newborns and review of the literature (MEDLINE and LILACS).

Two cases of newborns with huge abdominal masses are presented, one of them complicated by rupture and hemorrhage during ultrasound manipulation, leading to hypovolemic shock. Urgent operation showed a ruptured giant hepatic cyst containing hemorrhagic yellowish fluid. The cyst was removed by edge resection at the level of hepatic segment 6 and the postoperative period was uneventful. The pathological analysis of the cyst including immunohistochemical tests revealed HMH. In case 2, with prenatal diagnosis of hepatic tumor, the mass progressively enlarged after birth, and a left hepatectomy was performed. The macroscopic appearance suggested hemangioma but the histopathological aspect indicated mesenchymal hamartoma with endothelial predominance. Nowadays both children are healthy and asymptomatic.

The management of HMH is surgical treatment, because it does not disappear spontaneously. Some cases evolve to giant forms even in the neonatal period leading to fatal complications. Preoperative differential diagnosis from hemangioma is quite difficult for cystic types, and immunohistochemical analysis is important for pathological confirmation.