Mesenchymal hamartoma

Clinical features

  • 8% of paediatric liver tumours
  • 75% in patients less than one year of age
  • 10-20% present at birth
  • 75% in the right liver lobe
  • Abdominal mass
  • Benign
  • Association with placental anomalies
  • Most cases have no association with malformations

 

Cytopathology

  • Monotonous population of spindle cells in clusters
  • Pointed-end fusiform nuclei
  • Myxoid proteinaceous background may be present

 

Immunocytochemistry

  • Vimentin: positive

 

Genetic studies

  • Breakpoint on chromosome 19

 

Differential diagnosis

  • Hemangioendothelioma
    • Typically occurs before six months of age
  • Inflammatory pseudotumor
    • Mesenchymal hamartoma is generally devoided of the inflammatory polymorphic population that characterizes inflammatory pseudotumor. However, rare cases of mesenchymal hamartoma may have extra medullary haematopoiesis, thus creating confusion
  • Embryonal sarcoma
    • Highly aggressive appearance in smears: mitosis, necrosis and cellular pleomorphism
    • Hyaline globules
  • Hepatic smooth muscle tumours (leiomyoma’s and leiomyosarcomas)
    • Rare cases have been described associated with HIV in children
    • Smooth muscle actin: positive

 

Main points

  • Excision is curative but with high morbidity
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