Correlation of vascular morphology with clinical types in cholesteatoma of the middle ear.

Cholesteatoma is characterized by the presence of hyperproliferative keratinizing squamous epithelium in the middle ear cavity. The abundance and morphology of blood vessels in the stroma of cholesteatoma was investigated using a monoclonal antibody against an endothelial cell marker, factor VIII-related antigen. Normal skin sections were stained for comparison. In cholesteatoma tissue blood vessels frequently were more numerous and smaller in caliber than in normal skin. The pattern of vascularization differed between the pearly and the dendritic type of cholesteatoma. In the dendritic type capillaries with uniform diameter prevailed, whereas the pearly type showed blood vessels of variable caliber with a clearly visible lumen. This hypervascularization observed in cholesteatoma may be induced by factors released from infiltrating immune cells and the squamous epithelium and could play an important role in sustaining the continuous abnormal growth of the cholesteatoma.