Minute pulmonary meningothelial-like nodules: clinicopathologic analysis of 121 patients

Minute pulmonary meningothelial-like nodules (MPMNs) are generally detected incidentally in resected lung specimens. With the development of diagnostic radiology, MPMNs have occasionally been detected on thin-section computed tomography. Their clinicopathologic background remains unclear because there have been no reports of a large series of patients with them. Among 1724 pulmonary resections during a 4 1/2 year period, 271 MPMNs were identified in 121 patients (7.0%) after pathologic examination. Minute pulmonary meningothelial-like nodules were seen more often in females than in males (10.7% versus 4.5%; odds ratio, 2.01; 95% confidence interval, 1.36-2.97; P < .001). Minute pulmonary meningothelial-like nodules were present in all lobes, and the frequency of incidence was not different between lobes. The incidence frequency of MPMNs was not different between age groups. Minute pulmonary meningothelial-like nodules were found more often in patients with malignant pulmonary tumors than in those with benign disease (7.3% versus 2.5%; P = .044). In particular, MPMNs were found more often in patients with lung adenocarcinoma than with other primary pulmonary malignant tumors (9.4% versus 4.5%; odds ratio, 2.33; 95% confidence interval, 1.35-4.02; P < .01). There was no significant difference in clinicopathologic factors between patients with single and multiple MPMNs, except for the size of each nodule.