Hepatic Mesenchymal Hamartoma With Elevated Alpha-Fetoprotein: A Diagnostic Dilemma

Hepatic mesenchymal hamartoma (HMH) is an uncommon, benign liver tumor predominantly affecting children under three years of age. It is characterized histologically by disorganized mesenchymal stroma, abnormal bile ducts, blood vessels, and hepatocytes. HMH can present as a large cystic mass, a solid mass, or a combination of both. Hepatoblastoma, the most common malignant liver tumor in children, remains a primary differential diagnosis. This case report highlights the diagnostic challenge presented by HMH, particularly when alpha-fetoprotein levels are mildly elevated. A two-year-old male presented with abdominal distension and a palpable mass, with initial ultrasound imaging revealing a large cystic and solid liver lesion. Contrast-enhanced computed tomography showed a well-defined mass with both cystic and solid components arising from the liver with a large exophytic soft tissue component extending and occupying the majority of the abdominal cavity, raising the possibility of HMH and hepatoblastoma. Histological examination confirmed HMH, with no malignancy identified. This case emphasizes the crucial role of imaging and histopathology in differentiating HMH from other hepatic lesions. Although HMH generally has an excellent prognosis with complete surgical resection, it may rarely undergo malignant transformation, necessitating careful diagnostic evaluation and management.