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Mesenchymal hamartoma of the liver--new insight into histogenesis
D von Schweinitz1, B G Dammeier, S Glüer
1Department of Pediatric Surgery, Medical School Hannover, Germany.
Background/Purpose:
Mesenchymal hamartoma (MH) of the liver is thought to develop from the ductal plates of the prenatal liver. This immunohistochemical study was performed to gain insight into the pathophysiology of its development.
Methods:
Specimens from four MHs with adjacent liver, in one case from a biopsy and from the resected lesion after 6 years follow-up, were investigated with immunostaining on cryostatsectionswith antibodies against cytokeratins, vimentin, desmin and alpha-actin, as well as von Willebrand factor (factor VIII), fibroblast growth factor (FGF) receptors, FGF-1 (acidic FGF), FGF-2 (basic FGF), and the proliferation-associated Ki67 antigen.
Results:
Fibrous tissue of MH stained positive not only for vimentin, but also for desmin and alpha-actin, whereas cytokeratins and factor VIII showed specific staining in biliary cysts and endothelial cells, respectively. All mesenchymal cells expressed proteins of the FGF receptor family. Although FGF-1 was only scarcely detectable, there was an accumulation of FGF-2 in borderline areas of liver to MH. Multiple Ki67-positive mesenchymal cells could be identified in these regions in all three MHs. However, we could not detect any proliferative activity in the MHs after follow-up.
Conclusions:
The proliferative process in MH is still active during early childhood. FGF-2 may have a role in promoting this process. The positivity for desmin and alpha-actin of the lesions suggests that fat-storing (Ito) cells of the immature liver may be involved in the development of MH.
Insights
Mesenchymal hamartoma (MH) of the liver shows active proliferation in early childhood, potentially involving fat-storing cells and driven by FGF-2. This study investigates the pathophysiology of MH development.
Area of Science:
- Hepatology
- Developmental Biology
- Immunohistochemistry
Background:
- Mesenchymal hamartoma (MH) of the liver is a congenital tumor.
- Its development is hypothesized to originate from prenatal liver ductal plates.
- This study investigates the pathophysiology of MH development using immunohistochemistry.
Observation:
- Immunostaining of MH specimens revealed vimentin, desmin, and alpha-actin in fibrous tissue.
- Cytokeratins and factor VIII stained biliary cysts and endothelial cells, respectively.
- Mesenchymal cells expressed FGF receptor family proteins, with FGF-2 accumulation at liver-MH borders.
Findings:
- Ki67-positive mesenchymal cells were identified at liver-MH borders, indicating proliferation.
- Proliferative activity was not detected in MHs after follow-up.
- Positivity for desmin and alpha-actin suggests involvement of immature liver fat-storing (Ito) cells.
Implications:
- The proliferative process in MH is active in early childhood.
- Fibroblast growth factor-2 (FGF-2) may play a role in promoting MH proliferation.
- Understanding MH pathophysiology can inform future therapeutic strategies.