- Benign, complex multicystic mass with poor enhancement
- Mix of mesenchymal and epithelial elements
- Present before 2 years of age
Description
Hepatic mesenchymal hamartoma is a rare benign tumour of the liver, most commonly diagnosed in infancy and early childhood. It is characterised by a combination of cystic spaces and mesenchymal stroma, often with some degree of hepatocyte involvement.
Pathogenesis
The exact pathogenesis is unknown, but it is believed to represent a developmental anomaly rather than a true neoplasm. It may result from an imbalance in the proliferation of mesenchymal and epithelial components of the liver during fetal development.
Epidemiology, Risk Factors & Associations
- Predominantly affects infants and young children, with most cases diagnosed before the age of 2.
- Male predominance
- Rarely associated with other congenital anomalies.
Clinical Features
- Often asymptomatic and discovered incidentally during imaging for unrelated reasons.
- Can present with a palpable abdominal mass or abdominal distension.
- Rarely, may cause respiratory distress due to mass effect on the diaphragm.
Complications
- Potential for significant growth, leading to abdominal discomfort or distension.
- Rare reports of malignant transformation.
- Possible compression of adjacent organs, leading to gastrointestinal or respiratory symptoms.
Pathological Features
Histopathology
- Macroscopic: A well-circumscribed, multicystic lesion, sometimes with solid areas.
- Microscopic: Composed of cystic spaces lined by biliary epithelium and separated by loose mesenchymal stroma that may contain islands of normal hepatocytes.
Serology
- AFP may be mildly elevated
Radiological Features
General Features
- A large, multicystic lesion within the liver, often with septations and solid components.
- Calcifications are rare
US
- Shows a complex, multicystic mass with varying echogenicity due to the presence of both fluid-filled cysts and solid areas.
CT
- Non-contrast: May demonstrate a well-circumscribed mass with cystic and solid components.
- C+ Arterial/Venous: The solid components and septa may enhance.
Grading and Staging
- Not applicable due to its benign nature.
Diagnosis
- Predominantly based on imaging findings.
- Histopathological confirmation may be required to differentiate it from other hepatic lesions, especially in cases where malignancy cannot be ruled out based on imaging alone.
Differential Diagnosis
- Hepatoblastoma: More common in the same age group but typically presents as a solid, avidly-enhancing tumour with aggressive behaviour (vs. poor enhancement). Calcifications are common (vs. rare). AFP is usually elevated (vs. not usually elevated).
- Infantile hepatic haemangioma: Also diagnosed before 2 years of age.
- Congenital hepatic cysts: Present as simple cysts without the solid component.
- Cystic biliary atresia: Associated with jaundice and other signs of biliary obstruction.
Management
- Surgical resection is the treatment of choice, especially for symptomatic lesions or when malignancy cannot be excluded.
- Asymptomatic, small lesions may be monitored with serial imaging due to the potential for spontaneous regression.
- Complete resection is usually curative with an excellent prognosis.