Contrarily, CD70 negative tumour cells (0–10%) were mostly observed in prostate carcinoma (75%, N = 12), Langerhans cell histiocytosis (80%, N = 5), Kaposi sarcoma (100%, N = 7), and colorectal carcinoma (80%, N = 75), whereby a significant lower expression of CD70 was observed in the latter two groups as compared to all other tumour types (p = 0.012 and p < 0.0001, respectively). Here, CD70 is linked to Kaposi's sarcoma.