Peripheral vs central squamous cell carcinoma of the lung. A comparison of clinical features, histopathology, and survival.

We reviewed the clinical features and histopathologic findings of 21 peripheral pulmonary squamous cell carcinomas (SCC) resected at our institution between 1961 and 1981 and compared them with 19 central SCCs. Histologic features were scored semiquantitatively from 0 to 3+. Peripheral SCC represented 16% of all resected SCCs. The proportion of patients with multiple symptoms was lower and survival during the 5 years after surgery was better in the peripheral group. Tumor size, mitoses per high-power field (2.4 +/- 0.3 vs 4.1 +/- 0.6 [SEM]), prevalence of lymphatic invasion (19% vs 58%), and lymph node metastases (5% vs 37%) were lower, while chest wall invasion was more frequent (25% vs 0) for peripheral SCCs. Peripheral tumors also had more intense (2 or 3+) lymphoplasmacytic (86% vs 47%) and desmoplastic (95% vs 68%) reactions. Cox regression analysis did not support a significant relationship between tumor location and survival. We conclude that, compared with the central SCC, peripheral SCC is associated with fewer symptoms at presentation and better survival. Morphologically, peripheral SCCs are smaller, have fewer mitoses, less prevalent lymphatic invasion, and a more intense stromal reaction. Improved survival in patients with peripheral SCC may be due to a more favorable stage at the time of initial treatment.