Pleomorphic hyalinizing angiectatic tumor of soft parts : Immunohistochemical study including the expression of vascular endothelial growth factor

c We report morphologic, flow cytometric, and immunohistochemical findings in two cases of pleomorphic hyalinizingangiectatic tumor of soft parts. Both patients were middle-aged women with subcutaneous lesions located in the lower extremity. The tumors consisted of sheets of spindled and pleomorphic cells with frequent intranuclear pseudoinclusions associated with clusters of ectatic vessels surrounded by prominent perivascular hyalinematerial. Numerous, nonhyalinized vessels were also present, mostly in the peripheral areas of the lesions. Some of these vessels had their walls permeated by numerous small capillaries. Immunostaining for vascular endothelial growth factor (VEGF), a secreted protein that has been implicated in tumor-associated angiogenesis, demonstrated positive staining in both tumoral and endothelial cells. Tumor cells were also reactive to vimentin and CD34. Focal positivity for CD99and factor XIIIawas also present. Flow cytometry yielded a diploid DNA histogram with S-phase fraction of 7%. Our findings corroborate those from previously reported cases. They further suggest that angiogenesis and the angiogenic factor VEGF may play a role in the development of this peculiar tumor. (Arch Pathol Lab Med. 2000;124:423‐426)