RESUMO
BACKGROUND: CD34 is a 115 kD glycoprotein which is expressed on hematopoietic progenitor cells. It is also known as an immunohistochemical marker of endothelial cells. OBJECTIVE: This study was designed to investigate the patterns of CD34 expression on: (1) cutaneous benign and malignant vascular tumors and (2) on the mature and immature vessels of pyogenic grauloma and capillary hemangioma. METHOD: We performed immunoperoxidase staining using a monoclonal anti-CD34 antibody (QBEND/10) on formalin fixed, paraffin-embedded sections of 23 benign and malignant cutaneous vascular tumors. RESULTS: The results are summerized as follows: 1. In 3 cases of nevus flammeus and 6 cases of carvernous hemangioma, vascular endothelial cells of all hemangiomas showed CD34 expressions. In 5 cases of angiokeratoma, endothelial cells of hemangioma, did not express CD34. 2. In all 5 cases of pyogenic granulomas and one case of capillary hemangioma, endothelial cells of mature vessels, endothelial cells near the well-formed lumina and endothelial cells showing intracellular lumina showed strong positivity for CD34, wbile endothelial cells far from the lumina and endothelial cells without lumina formation mostly showed negative staining for CD34. 3. One cese of Kaposis sarcoma showed focall positivity for CD34 both in endothelial cells of the small, well-formed vessels and spindle cells. Two cases of angiosarcoma showed CD34 expression only in endothelial cells of well-formed, normal appearing vessels, whereas atypical endothelial cells of tumor vessels and spindle cells were negative for CD34. CONCLUSION: CD34 could be a marker for endothelium in mature, well-differentiated vascular structures and may serve as a marker of lumen formation or differentiation of endothelial cells.