p63 has been shown to be a sensitive marker for lung squamous cell carcinomas (SqCC), with reported sensitivities of 80-100% (1-6). Specificity for lung SqCC, versus lung adenocarcinoma (LADC), has been reported to be approximately 70-90%, as positive staining with p63 has been typically observed in 10-30% of LADC (1-6). Cocktails of p63 with complementary markers for lung SqCC have also proven useful. A cocktail of p63 TRIM29 demonstrated a 94.7% sensitivity for lung SqCC and 100% specificity versus LADC, in cases where Napsin A and TTF-1 were both negative (2-7). Similarly, the combination of p63 CK5 identified 87% of cases of lung SqCC, with 94% specificity (8).