Proliferation and apoptosis within juvenile capillary hemangiomas

Capillary hemangiomas (CH) are benign vascular neoplasms of childhood that undergo a natural course of postnatal growth followed by spontaneous involution and often complete regression. There are currently no established standards for the identification of the growth phase of CH. We retrospectively examined 24 CH specimens for staining with MIB1, a monoclonal antibody directed at the same proliferation-related antigen as Ki-67, and antibody to bcl-2, a protooncogene product associated with inhibition of cellular apoptosis, and correlated these findings with the growth phase. All lesions demonstrated more positivity with MIB1 than with bcl-2, with more prominent staining in interstitial cells and an inverse correlation with increasing age. When calculations were adjusted for vascular lumina predominance, staining similarly decreased but at a later age. Our study supports interstitial cell-predominant proliferation within CH. In addition, bcl-2 expression was demonstrated, also interstitially predominant, and showed a decrease with aging, suggesting that programmed cellular death is involved in the growth regulation of these lesions and that regression is associated with changes in both proliferation and apoptosis. Last, both proliferation and bcl-2 expression showed a marked decrease later in more vascular channel-predominant lesions, possibly suggesting that such lesions undergo longer periods of growth before entering the involutional phase.