HRCT findings of small cell lung cancer measuring 30 mm or less located in the peripheral lung

Purpose To evaluate the high-resolution CT (HRCT) features of peripherally located small cell lung cancer (SCLC). Materials and methods We retrospectively reviewed the HRCT findings of 33 patients with peripherally located SCLC measuring 30 mm or less. The shape and marginal and internal characteristics of the nodules were evaluated. We also assessed the differences in these HRCT findings associated with the differences in the stages of disease. In 10 surgically treated cases, the HRCT-pathological correlations were evaluated. Results The findings of a well-defined margin (97.0 %), lobulation (78.8 %), thickening of the bronchovascular bundle (BVB) (57.6 %) and inhomogeneous enhancement (64.0 %) were common. A vermiform/branching and polygonal shape were observed in 33.3 and 21.2 % of cases, respectively. Air bronchograms (15.2 %) and marginal ground-glass opacity (GGO) (3.0 %) were less common findings. The vermiform/branching shape and thickening of the BVB were more frequently observed in non-stage I than in stage I tumors. The pathologic findings showed expansive tumor growth along the lymphatics and minimal necrosis between the tumor nests. Conclusion A non-round shape and thickening of the BVB were common, while marginal GGO and air bronchogram were less common in small-sized, peripherally located SCLC. Furthermore, the vermiform/branching shape and thickening of the BVB suggested relatively advanced disease.