CD34 and dermatofibrosarcoma protuberans: As CD34 is also widely expressed in other vascular tumors (66, 83, 129, 141) and non-vascular cancer cell types (e.g., fibroblastic tumors, gastrointestinal stroma tumors, dermatofibrosarcoma) (206, 207), positivity for CD34 alone does not confirm AS diagnosis.