PTPRC and head and neck squamous cell carcinoma: The absolute number of CD45+ lymphocytes per microgram tissue was highly heterogeneous in HNSCC, ranging from 0.1 cells/μg to 44.2 cells/μg with an average of 5.2 ± 8.9 cells/μg, which was significantly higher than the number of CD45+ cells in randomly biopsied non-cancerous mucosa samples (n = 7, 0.3 ± 0.2/μg; p = 0.004; Figure 1A).