CD34 and dermatofibrosarcoma protuberans: Firstly, Cerio et al. demonstrated by immunohistochemical staining of 30 patient samples that numerous dermal cells of DF samples react with anti-FXIII-A antibodies [89], which (together with the hematopoietic stem cell marker CD34) gained importance in the differential diagnosis for dermatofibrosarcoma (DFSP), where tumor cells were negative for FXIII-A and positive for CD34 [90,91,92].