Immunohistochemical study of some rare vascular tumors.

PURPOSE Kaposiform-hemangioendothelioma (KHE) is a rare vascular tumor,developing predominantly in infants and children. Despite its benign histology, this tumor frequently behaves aggressively,causing significant morbidity and mortality. The striking resemblance of its spindle cell proliferation to that seen in Kaposi Sarcoma (KS) led to the designation of KHE for this rare lesion. This work examined the histopathologic features of KHE and KS and assessed the value of some vascular immunohistochemical markers such as CD34,CD31 and factor VIII associated antigen in routine diagnosis and differential diagnosis of these vascular tumors. MATERIAL AND METHODS Three cases of KHE and twenty cases of KS were included in this study. All specimens are fixed in formalin,embedded in paraffin wax and stained with Hematoxlin and eosin and reticulin stains. The antibodies to CD34,CD31 and factor VIII associated antigen were applied using the streptavidin biotin technique. RESULTS Immunohistochemically,all elememts within the lesions were labeled with anti-CD34 antibody. Labeling of spindle cells was less consistent with anti-CD31,while the antibody to factor VIII associated antigen labeled only the well formed capillaries. CONCLUSIONS KHE and KS are tumors of endothelial cell origin. Immuno-staning for CD34 and to a lesser extend,CD31,are more reliable for labeling KHE and KS than the traditional endothelial cell marker, factor VIII associated antigen. These markers can be used for diagnosis in routinely processed tissue of KS and KHE.