Mesenchymal hamartoma of the liver in infants.

Mesenchymal hamartoma of the liver is a rare benign tumor of childhood which has been confused with various other benign liver lesions, particularly vascular hamartomas which are mesodermal but not mesenchymal. The mass, frequently cystic, is characterized by an admixture of epithelial structures in a loose connective tissue stroma with fluid accumulation suggestive of lymphangiomatous channels. Four patients are presented and reviewed with 25 previously reported cases. The patients, usually asymptomatic, present during the first two years of life with progressive abdominal distention, which may be rapid because of increasing fluid content in the connective tissue stroma and cysts. Exploration and biopsy may be necessary before definitive excision. The present cases include a newborn, the youngest known, and a case in which radiation resulted in hyalinization of the mesenchyme, decrease in fluid content, and easlier resection. Respiratory distress and signs of vena caval obstruction due to intra-abdominal pressure were noted. Prognosis after extirpation is very good.