PECAM1 and Kaposi's sarcoma: On hospital day 6, the immunostaining results from biopsy revealed submucosal spindle cells that were negative for CAM 5.2 (low molecular weight cytokeratin), 34 betaE12 (high molecular weight cytokeratin), p-40 (squamous cell carcinoma marker), and SOX-10 (melanoma marker), while they were positive for CD-31 (endothelial/vascular marker), supporting the morphological diagnosis of KS.