Heterogenous expression of endothelial cell markers in infantile hemangioendothelioma. Immunohistochemical study of two solitary cases and one multiple one.

Three cases of infantile hemangioendothelioma were immunohistochemically studied with the use of antibodies against von Willebrand factor (vWF), Ulex europaeus I lectin (UEA I), vimentin, thrombomodulin (TM), and actin, as endothelial cell (EC) markers. Because of a broad variety of histologic features, the growth pattern of the tumor cells was subclassified into the following four subtypes: capillary, sinusoidal, cavernous, and myxomatous parts. The solitary tumor from patients 1 and 2 was composed of these four components, but the multiple tumor in the patient 3 consisted of capillary and sinusoidal parts. Immunohistochemically, vWF and vimentin were dominantly expressed in the ECs of the cavernous and myxomatous parts. UEA I had strongly positive results in all histologic types, except the myxomatous part. Expression of vWF and vimentin in neoplastic EC suggests that functional differentiation of the tumor tissue occurs in the myxomatous and cavernous parts and may be related to the spontaneous regression of the infantile hemangioendothelioma.