Mesenchymal hamartoma of the liver occurs almost exclusively in infancy and childhood, with approximately 140 total cases reported. We report the experience with 18 patients at the Childrens Hospital of Los Angeles (Calif) during the past 35 years. The charts of all patients with mesenchymal hamartoma were retrospectively reviewed. The mean age at presentation was 16 months. Thirteen patients were symptomatic, presenting with increasing abdominal distention. Physical examination revealed an abdominal mass or hepatomegaly. Ultrasonography and computed tomography were the most useful diagnostic tests. Fourteen patients underwent resection; 9 underwent hepatic resection and 5 underwent excision of the tumor only. One patient had marsupialization, 1 underwent a biopsy only, and 2 died of unrelated causes and the hamartoma was found incidentally at autopsy. In all instances, a large cystic mass with well-demarcated margins was found. Three patients were unavailable for follow-up and 13 patients were alive and well 1 month to 24 years (mean, 5 years) after diagnosis. Recurrence or malignant transformation was not noted. A presumptive diagnosis can be made preoperatively by normal laboratory values and a combination of ultrasonography and computed tomography VSports手机版. We recommend excision of the tumor in all patients once the diagnosis is made, with the expectation of complete recovery. .