Mesothelial cyst of the liver in a neonate.

Mesothelial cysts are very rare congenital cystic lesions that are derived from coelomic remnants. We report a neonate with a mesothelial cyst of hepatic origin. On routine antenatal ultrasound study, an intra-abdominal mass was seen. After birth, the cystic lesion's size increased to 8 cm and became symptomatic. Surgical resection was performed. Preoperative diagnostic imaging studies, including CT and MRI, did not identify the etiology, but the cyst appeared to be of hepatic origin. Intra-operatively, the cystic lesion was confirmed to have originated from the liver. Based on immunohistological analysis, the final diagnosis was mesothelial cyst of the liver.