Giant hepatic mesenchymal hamartoma in a preterm newborn: a case report and literature review.

Mesenchymal hamartoma of the liver (MHL) often presents as a painless right upper abdominal mass in young children. However, MHL is rarely reported in the neonatal period. We presented the case of a preterm newborn with a huge MHL. The boy was delivered at 30 weeks weighing 1750 g. Abdominal distention was the initial presentation. Ultrasound and computed tomography showed a highly vascularized mass originating from the left lobe. Liver hemangioma was initially suspected and oral propranolol was administered. However, the tumor was rapidly enlarging, resulting in compromised respiratory status and severe anemia. Surgical resection and neonatal management were successful. The patient required cardiopulmonary resuscitation in the operating room and received packed red blood cells. The histopathological result was mesenchymal hamartoma. The baby recovered well after one-year follow-up. We also reviewed the clinical courses and treatment strategies of preterm MHL cases in published English literature from 1990 to 2021.