D2-40 immunohistochemical analysis of pediatric vascular tumors reveals positivity in kaposiform hemangioendothelioma.

Kaposiform hemangioendothelioma is a distinctive vascular neoplasm affecting predominantly children and neonates. In neonates it needs to be differentiated from common infantile hemangioma and other vascular lesions of infancy. Kaposiform hemangioendothelioma immunoreacts with vascular endothelial growth factor receptor 3, and partial lymphothelial differentiation of this lesion has been suggested. D2-40 has been recently proposed as a selective marker of lymphatic endothelium. We performed immunohistochemical analysis with the D2-40 antibody on 24 kaposiform hemangioendotheliomas and 48 other pediatric vascular lesions including common infantile hemangioma (n=10), rapidly involuting congenital hemangioma (n=10), non-involuting congenital hemangioma (n=9), verrucous hemangioma (n=9), and pyogenic granuloma (n=10) to define whether this marker can be applied in the diagnosis of vascular lesions of infancy. In all, 23 of 24 (96%) kaposiform hemangioendotheliomas exhibited a distinct staining, while none of the other lesions immunoreacted with D2-40. D2-40 stained the neoplastic spindled cells and lymphatic channels adjacent to vascular lobules of kaposiform hemangioendothelioma. These findings support D2-40 as a new determinate marker for kaposiform hemangioendothelioma, useful in differentiating it from other vascular lesions of infancy and suggest lymphothelial differentiation of the neoplastic component of kaposiform hemangioendothelioma. Further studies are necessary to define the identity of the D2-40 antigen and to elucidate the biologic significance of its selective lymphothelial reactivity..