Clinicopathological and immunophenotypic characteristics of minute pulmonary meningothelial-like nodules comorbid with lung adenocarcinoma

OBJECTIVE: The aim of this study was to delineate the clinicopathological features and diagnostic immunophenotype of minute pulmonary meningothelial-like nodules (MPMNs), particularly with lung adenocarcinoma. METHODS: A retrospective evaluation was performed on nine cases of MPMNs diagnosed between 2017 and 2021. Data included imaging findings, histomorphological characteristics, and immunohistochemical (IHC) profiles. A literature review was conducted to examine diagnostic and differential diagnostic considerations. RESULTS: Of the 9 patients, 6 (66.7%) were female, yielding a male-to-female ratio of 1:2. The mean age was 65.6 ± 9.0 years. Pulmonary adenocarcinoma was concurrently identified in eight cases (88.9%). Common comorbidities included hypertension (66.7%), cerebral infarction (33.3%), and diabetes mellitus (22.2%). Among those with hypertension, 83.3% (5/6) had received treatment with dihydropyridines. Lesions were more frequently located in the right lung (55.6%), with ground-glass nodules observed in 55.6% of cases on computed tomography. All cases were confirmed by histopathological analysis following thoracoscopic segmentectomy or lobectomy. Histologically, the nodules measured 0.10–0.50 cm and were well-circumscribed, consisting of short spindle-shaped cells arranged in whorled or nested patterns. IHC indicated consistent positivity for vimentin and epithelial membrane antigen in all cases (100%), partial positivity for CD56 (66.7%), and negativity for SMA and cytokeratin. CONCLUSIONS: MPMNs represent benign lesions, most commonly identified in older adult females and frequently associated with pulmonary adenocarcinoma. Imaging findings are non-specific, and definitive diagnosis relies on histopathological and IHC features, notably vimentin+/EMA+/CK − expression profiles.