Table 2.

Histological findings of central and peripheral squamous cell carcinomas.

	Central	Peripheral	P value
	Positive cases/total cases (%)
Alveolar filling pattern	1/12 (8)	8/30 (27)	0.16
Infiltrating pattern	11/12 (92)	22/30 (73)	0.16
Inflammation	9/12 (75)	25/30 (83)	0.85
Necrosis	12/12 (100)	27/30 (90)	0.35
Fibrosis inside the tumor	12/12 (100)	28/30 (93)	0.51
Keratinization	8/12 (67)	19/30 (63)	0.57
Capsule	3/12 (25)	4/30 (13)	0.91
Background lung fibrosis	4/11 (36)	14/30 (47)	0.41
Traction bronchiectasis	6/11 (55)	9/30 (30)	0.14
Visceral pleural invasion	7/15 (47)	19/35 (54)	0.62
Emphysema (microscopic)	6/13 (46)	24/31 (77)	0.039
Interstitial pneumonia (microscopic)	2/13 (15)	17/31 (55)	0.015