Hepatic hemangioma pathophysiology

Development of hepatic hemangioma is the result of genetic mutations, overexpression of angiogenic fators and downregulation of inhibitors of angiogenesis.^[1] Hepatic hemangioma may be associated with Kasabach-Merritt syndrome, hereditary hemorrhagic telangiectasia, hepatic arterio-portal shunts, extra hepatic hemangiomata, hemolytic anemia, focal nodular hyperplasia.^[2] On gross pathology, variable in size, well circumscribed, and classically subcapsular are findings of hepatic hemangioma.^[3] On microscopic histopathological analysis channels lined by benign endothelium containing RBCs, surrounding (non-endothelial) cells without significant atypia are findings of hepatic hemangioma.^[4]

The pathogenesis of hepatic hemangiomas has not been elucidated, but there are two competing theories.

• The first theory supports the notion that hepatic hemangioma may be the result of overexpression of angiogenic factors and downregulation of inhibitors of angiogenesis.

• Overexpression of angiographic factors, such as:^[1]

• Vascular endothelial growth factor
• Basic fibroblast growth factor
• Metalloproteinases

• Downregulation of inhibitors of angiogenesis, such as:^[1]

• Tissue inhibitor of metalloproteinase-I

• The second theory suggests that the presence of liver hemangiomas involves a genetic background of mutations.^[1]

• Metalloproteinases accumulate in the endoplasmic reticulum of the tumor cells. Accumulation may result in the following:

• Self-digestion
• Vacuole formation

• Cavernous hemangioma cell to downregulate Derlin-1.

• Derlin-1 is a protein encoded by DERL1. When overexpressed, derlin-1 protein induces the dilated endoplasmic reticulum to return to its normal size.

Hepatic hemangioma may be associated with:^[2]

• Kasabach-Merritt syndrome
• Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease)
• Hepatic arterio-portal shunts
• Extra hepatic hemangiomata
• Hemolytic anemia
• Consumptive coagulopathy
• Focal nodular hyperplasia

On gross pathology, a well circumscribed, subcapsular tumor may be suggestive of hepatic hemangioma.^[3]

On microscopic histopathological analysis channels lined by benign endothelium containing RBCs, surrounding (non-endothelial) cells without significant atypia are findings of hepatic hemangioma.^[4]

• 
  Intermediate magnification micrograph of a cavernous hemangioma of the liver, also hepatic cavernous hemangioma, liver hemangioma,cavernous liver hemangioma. H&E stain. No liver tissue is observed.^[4]
• 
  High magnification micrograph of a cavernous hemangioma of the liver, also hepatic cavernous hemangioma, liver hemangioma,cavernous liver hemangioma. H&E stain. No liver tissue is observed.^[4]