Accurate diagnosis of peripheral small cell lung cancer with computed tomography

Small lesions are frequently detected in the lung with computed tomography (CT) in clinical practice. It is important to know the CT features of small-sized peripheral small cell lung cancer (SCLC) for early-stage diagnosis. We reviewed the CT findings of SCLC that presented as a solitary peripheral nodule without associated lymphadenopathy. This study included 12 patients (11 men and 1 woman; mean age, 68.5 years) with peripheral SCLC of diameters ranging from 9 - 28 mm (mean, 15.4 mm). We evaluated the findings with thin-section CT for each peripheral tumor; emphasis was laid on the predominant internal characteristics (whether the mass is solid), tumor-lung interface characteristics (whether the mass is well-defined with a smooth surface or with lobulation or spiculation), and surrounding structures (the presence or absence of perivascular thickening adjacent to the tumor). In all patients, most portions of the tumor consisted of a non-calcified solid mass. Contrast enhancement in varying degrees was observed in the tumors of all 8 patients, who were evaluated with enhanced CT. The tumor-lung interface characteristics observed on the CT images included a well-defined mass with a smooth surface (n = 5), a well-defined mass with lobulation (n = 3), and a mass with spiculation (n = 4). An irregular perivascular thickening adjacent to the tumor was observed in 4 patients. We conclude that peripheral SCLC without associated lymphadenopathy manifests as a non-calcified solid mass and is occasionally characterized by perivascular thickening.