Similar though larger cysts in adjacent sections had no discernible lining. Figure 8 Foci of extramedullary hematopoiesis, including megakaryocyte precursors are present in the mesenchymal tissue. Figure 9 Remnants of bile ducts are compressed by some of the hyaline-like mesenchymal tissue. Discussion Clinical Mesenchymal hamartoma of the liver is a benign lesion seen in young infants with a history of increasing abdominal distention. The lesions are large, usually multicystic masses of loose mesenchymal tissue containing small bile ducts and variable sized spaces filled with serous fluid.
Surgical resection is curative and there is no convincing evidence of malignant transformation.
Only rarely are cases reported in children over 5 years of age. Only rarely are other symptoms present including vomiting, decreased appetite or respiratory distress. George and colleagues described a newborn who presented with ascites related to the rupture of a mesenchymal hamartoma. Mesenchymal hamartomas have been noted as an incidental finding at autopsy in six cases. Stocker and Ishak reported other anomalies or disease in 5 of 30 cases including adrenal cytomegaly, neonatal hyperbilirubinemia, endocardial fibroelastosis of the left ventricle, idiopathic thrombocytopenic purpura, and diffuse endocrinopathy.