Minute pulmonary meningothelial-like nodules simulating a metastatic lung adenocarcinoma: A case report

Minute pulmonary meningothelial-like nodules (MPMNs) are relatively rare lesions that located at the pleura or parenchyma of the lung. They are usually found incidentally at autopsy or in surgical specimens. We presented a case of asymptomatic 47-year-old woman with an abnormal shadow in the right upper lung field found by a routine chest X ray. A computed tomography (CT) scan of the thorax revealed a hyperdense subpleural mass, which histologically conformed to adenocarcinoma. A resection of the right upper lobe discovered preponderance of small multiple lesions under the pleura. Microscopically, they were an interstitial nodular proliferation of oval or spindle-shape cells arranged in a zellenballen nesting pattern near small veins. Immunohistochemical and cytological analyses confirmed the diagnosis of MPMNs. Coexistence of multiple MPMNs and lung adenocarcinoma can be a differential diagnostic problem due to suspected metastasis of the primary carcinoma. To obtain an accurate diagnosis, the clinical findings should completely conform to histological, immunohistochemical, and cytological ones.