Presence of local pleural adhesion in CT screening-detected small nodule in the lung periphery suggests noncancerous, inflammatory nature of the lesion

Purpose Differential diagnosis of small nodules in the lung periphery detected by low-dose chest CT screening is important before surgery. The aim of the study was to discriminate between benign and malignant lesions, identified in our preoperative imaging work-up examinations and confirmed during surgery, for nodules detected on CT screening. Materials and Methods This study is based on 106 patients (46 men and 60 women, median age: 61.5 years) with 123 CT screening-detected and histologically confirmed nodules smaller than 30 mm in the lung periphery identified between 2002 and 2005 at Azumi General Hospital, Japan. Lesions were classified into three groups according to histological findings: adenocarcinoma, atypical adenomatous hyperplasia (AAH) and inflammatory focal lesions. We examined the visceral pleura during surgery at a location close to lung nodules. Results The median diameter of resected lung nodules on high-resolution CT (HRCT) was 9.0 mm. Nodules were nonsolid in 42, partly solid in 51 and solid in 30. Histopathological diagnosis was lung cancer in 69, AAH in 21, other noninflammatory tumours in 6 and inflammatory lesions in 27. Fifty-four lesions were located in the subpleural zone. Eight of 123 nodules showed local pleural adhesions (LPA), while 2 were buried in extensive pleural adhesion. LPA was noted more frequently in inflammatory nodules than in cancer nodules (P<.01). Conclusion The presence of LPA in close proximity to a small nodule is indicative of noncancerous lesion. This feature allows the discrimination of pulmonary peripheral inflammatory lesion from peripheral small cancer on chest low-dose CT screening.