Intravascular papillary endothelial hyperplasia: a neoplastic "actor" representing an exaggerated attempt at recanalization mediated by basic fibroblast growth factor.

Intravascular papillary endothelial hyperplasia (IPEH), a lesion of the extremities often encountered by hand surgeons, is characterized histologically by a florid endothelial proliferation that is exclusively intravascular in location and suggests an exaggerated attempt at thrombus recanalization. The mechanism behind this exaggerated response is unknown. Prompted by an apparent increase in cases of IPEH noted at our hospital in the past 2 years and the availability of frozen tissue from these cases, we undertook studies of IPEH designed to better elucidate the pathogenesis of this neoplastic "actor." Studies of eight such lesions revealed them to be uniformly diploid by DNA flow cytometric analysis. Further studies of five pooled cases by Northern blot and immunoblot revealed a 5-10-fold increase in basic fibroblast growth factor transcripts (7.0 and 3.7 kb) and a 10-20-fold increase in immunoreactive basic fibroblast growth factor protein compared to that exhibited by non-IPEH organizing thrombi and cavernous hemangiomas. These results suggest that the pathogenesis of IPEH involves an autocrine loop of endothelial basic fibroblast growth factor secretion stimulating endothelial cell proliferation.