CDKN2A and neoplasm: In the remaining three tumours the unusual immunophenotype was resolved by molecular testing, specifically (i) subclonal p16 staining and wild type p53 staining in a tumour positive for HPV and with no TP53 mutation (HPV-A), (ii) negative p16 and wild type p53 staining with a TP53 mutation and negative for HPV (HPV-I), and (iii) equivocally increased p16 staining with mutant pattern p53 expression, negative HPV ISH and with a TP53 mutation (HPV-I).