PECAM-1 (CD31) Is Expressed on Proliferating Endothelial Cells, Stromal Spindle-Shaped Cells, and Dermal Dendrocytes in Kaposi's Sarcoma

To the Editor.— The platelet/endothelial cell adhesion molecule (PECAM-1) is a 130-kd glycoprotein (CD31) found on the surface of platelets, endothelial cells, and peripheral blood cells such as neutrophils and monocytes.¹⁻³Because of the expression on cultured endothelial cells and our interest in the reticuloendothelial cell system as it relates to Kaposi's sarcoma (KS),⁴,⁵we investigated the immunohistochemical staining pattern of CD31 in normal skin and cutaneous KS lesions. Subjects and Methods and Report of Results.— Six-millimeter punch biopsy specimens of skin (five normal healthy volunteers and four KS patch/plaque lesions from three different male patients, two with the acquired immunodeficiency syndrome and one with classic KS) were obtained after informed consent. The biopsy specimens were snap frozen in liquid nitrogen. A portion of a dermatofibrosarcoma protuberans was also obtained for comparison with the KS staining. Peripheral blood monocytes were obtained from the Ficoll-Hypaque interface of defibrinized venous