Table 3. Positive immunohistochemical staining of “adenocarcinoma markers” including TTF1, CK7, Napsin A and PE10 in p-SQCC compared to c-SQCC.

IHC markers	p-SQCC	c-SQCC	P
TTF1+	32/224 (14.3%)	30/386 (7.8%)	0.010
CK7+	58/165 (35.2%)	52/256 (20.3%)	0.001
Napsin A+	12/92 (13.0%)	9/126 (7.1%)	0.145
PE10+	15/220 (6.8%)	18/381 (4.7%)	0.278

IHC, immunohistochemical; p-SQCC, peripheral lung squamous cell carcinoma; c-SQCC, central lung squamous cell carcinoma.