High frequency of apoptosis in infantile capillary haemangioma.

Infantile capillary haemangioma (ICH) is a well-established clinicopathological entity which often regresses spontaneously. To elucidate the cause of spontaneous involution of ICH, the apoptotic and proliferative activities in seven cases of ICH were compared with those in five cases of lobular capillary haemangioma (LCH), using formalin-fixed paraffin-embedded tissue sections. The number of apoptotic cells detected by the modified in situ end-labelling method was significantly higher in ICH than in LCH, while the proliferative activities evaluated with mitosis and Ki-67 antigen expression did not differ significantly. Lewisy (Ley) antigen, an apoptosis-associated marker, was expressed in all cases of ICH but in none of LCH, while labelling for p53 protein and bcl-2 protein was almost completely negative in both tumours. These findings clearly demonstrate a much higher apoptotic activity in ICH than in LCH and suggest that apoptosis might be a cause of the spontaneous involution of ICH.