GLUT1: A newly discovered immunohistochemical marker for juvenile hemangiomas

Juvenile hemangiomas are common, benign vascular tumors of infancy. These l esions enlarge rapidly through cellular hyperplasia during the first year o f life and then involute over several years. Distinctive histopathologic fe atures of hemangiomas diminish during this evolution, and differentiation f rom vascular malformations becomes increasingly difficult. This distinction has important therapeutic implications, as juvenile hemangiomas differ fro m malformations in natural history and in potential for recurrence. We repo rt here that high endothelial immunoreactivity for the erythrocyte-type glu cose transporter protein GLUT1 is a specific feature of juvenile hemangioma s during all phases of these lesions. In a retrospective study, we found in tense endothelial GLUT1 immunoreactivity, involving more than 50% of lesion al microvessels, in 91% (139 of 143) of juvenile hemangiomas from patients aged 1 month to 11 years. No endothelial GLUT1 immunoreactivity was found i n any of 66 vascular malformations (17 arteriovenous, 33 venous, 11 lymphat ic, and 5 port-wine) from patients aged 5 days to 75 years, or in any of 20 pyogenic granulomas or 7 granulation tissue specimens. Abundant Ki-67 posi tivity in these latter lesions established that GLUT1 expression does not s imply reflect mitotically active endothelium. Focal GLUT1 immunoreactivity was found in 3 of 12 angiosarcomas, but not in any of 5 hemangioendotheliom as (epithelioid or infantile kaposiform). These findings establish GLUT1 im munoreactivity as a highly selective and diagnostically useful marker for j uvenile hemangiomas. Because high levels of endothelial GLUT1 expression in normal tissue are restricted to microvessels with blood-tissue barrier fun ction, these findings also have implications for the molecular and developm ental pathogenic mechanisms of juvenile hemangiomas. HUM PATHOL 31:11-22. C opyright (C) 2000 by WB, Saunders Company.