Mesenchymal Hamartoma
Hanlin L. Wang, MD, PhD
Key Facts
Etiology/Pathogenesis
Developmental anomaly vs. neoplasm
Recurrent balanced translocation involving chromosome band 19q13.4 or 19q13.3
Clinical Issues
Typically occurring in 1st 2 years of life, rarely seen in adults
Excellent prognosis after complete excision
Malignant transformation only in rare case reports
Macroscopic Features
Large, solid, &/or cystic hepatic lesion
Microscopic Pathology
Mixture of varying portions of mesenchymal cells, bile ducts, hepatocytes, blood vessels, and cystic spaces
Top Differential Diagnoses
Hepatoblastoma
 The cut surface of a large mesenchymal hamartoma shows numerous variably sized cystic spaces  admixed with solid areas. Minimal uninvolved liver tissue is present at the resection margin  . |
 Low-power view shows numerous bile ducts  in a loose, myxoid mesenchymal stroma. Note the presence of a large island of normal-appearing hepatocytes  within the tumor. |
TERMINOLOGY
Definitions
Benign mass lesion of liver primarily occurring in young children
ETIOLOGY/PATHOGENESIS
