Pathological diagnosis and immunohistochemical analysis of minute pulmonary meningothelial-like nodules: A case report.

Background: Minute Pulmonary Meningothelial-like Nodules (MPMNs) are rare benign pulmonary nodules, which are more common in elderly women and have a higher detection rate in lung tissues of patients with lung malignant diseases. Its origin is not yet clear. At present, there are few reports on the diagnostic methods such as imaging and pathological manifestations of MPMNs. This article reports a 70-year-old female patient with pulmonary adenocarcinoma combined with MPMNs and reviews of the relevant literature.

Case Summary: A 70-year-old women was admitted to our institution with feeling sour in her back and occasional cough for more than 2 mo. Computerized electronic scanning scan and 3D reconstruction images in our institution showed there were multiple ground-glass nodules in both of her two lungs. The biggest one was in the apicoposterior segment of left upper lobe, about 2.5 mm × 9 mm in size. We performed thoracoscopic resection of the left upper lung apicoposterior segment of the patient, and the final pathological report was minimally invasive adenocarcinoma. Re-examination of high resolution computed tomography 21 mo after surgery showed multiple ground-glass nodules in both lungs, and a new ground-glass nodule was found in the superior segment of the right lower lobe. We took pathological biopsy of the right upper lung and right lower lung nodules for the patient under thoracoscopy. The histomorphology of the right lower lobe nodule showed multiple lesions in the lung tissue, and the small foci in the alveolar septum were distributed in mild form of the aggregation of short spindle cells. The immunohistochemistry showed that the lesion was epithelial membrane antigen (EMA) (+), somatostatin receptor 2a (SSTR2a) (+), S-100 (-), chromogranin A (-), Syn (-), cytokeratin (-) and HMB-45 (-). The final diagnosis was minimally invasive adenocarcinoma, accompanied by MPMNs. We recommend that patients continue to receive treatment after surgery and to do regular follow-up observations.

Conclusion: The imaging manifestations of MPMNs are atypical, histomorphology and immunohistochemistry can assist in its diagnosis. This article reviews the relevant literature of MPMNs immunohistochemistry and shows that MPMNs are positive for EMA, SSTR2a, and progesterone receptor.