[Increase in alpha-actin and basic fibroblast growth factor in angiofibromas in patients with tuberous sclerosis]

We examined alpha-actin and an angiogenic factor, basic fibroblast growth factor (bFGF), by immunohistochemistry and Western blot analysis in four angiofibromas (AFs) and a connective tissue nevus (CTN) obtained from two patients with tuberous sclerosis (TS). There was an increase of alpha-actin-positive microvessels in the papillary and the upper reticular dermis of AFs and a CTN as compared to those in normal skin. The main localization of alpha-actin in the microvessels of AFs was considered to be pericytes. Many microvessels and a few interstitial fibroblast-like cells in frozen sections of AFs and a CTN were positively stained for bFGF, and most of the bFGF-positive microvessels corresponded to those containing alpha-actin as determined by double immunostaining. These data suggested a possible role of increased bFGF in stimulating angiogenesis and/or mainitaining vessels in AFs, although augmentation of mitotic activity was not noted by staining with Ki-67. Further investigations on the identification of the bFGF-producing cells and biological function of bFGF in AFs may be a clue to elucidate pathomechanisms of AFs.