Diffuse Pulmonary Meningotheliomatosis: Clinic-Pathologic Entity or Indolent Metastasis from Meningioma (or Both)?

Abstract

Pulmonary minute meningothelial-like nodules (MMNs) are common incidental findings in surgical specimens, consisting of tiny proliferation (usually no larger than 5–6 mm) of bland-looking meningothelial cells showing a perivenular and interstitial distribution, sharing morphologic, ultrastructural, and immunohistochemical profiles with meningiomas. The identification of multiple bilateral MMNs leading to an interstitial lung disease characterized by diffuse and micronodular/miliariform patterns radiologically allows the diagnosis of diffuse pulmonary meningotheliomatosis (DPM). Nevertheless, the lung is the most common site of metastatic primary intracranial meningioma, and differential diagnosis with DPM may be impossible without clinic–radiologic integration. Herein, we report four cases (three females; mean age, 57.5 years) fitting the criteria of DPM, all incidentally discovered and histologically evidenced on transbronchial biopsy (2) and surgical resection (2). All cases showed immunohistochemical expression of epithelial membrane antigen (EMA), progesterone receptor, and CD56. Notably, three of these patients had a proven or radiologically suspected intracranial meningioma; in two cases, it was discovered before, and in one case, after the diagnosis of DPM. An extensive literature review (44 patients with DPM) revealed similar cases with imaging studies excluding intracranial meningioma in only 9% (4 of 44 cases studied). The diagnosis of DPM requires close correlation with the clinic–radiologic data since a subset of cases coexist with or follow a previously diagnosed intracranial meningioma and, thus, may represent incidental and indolent metastatic deposits of meningioma.

Minute pulmonary meningothelial‐like nodule that was difficult to differentiate from lung adenocarcinoma due to specific computed tomography findings changes: A case report

“…Kakinuma et al 4 followed 1229 patients with GGN on CT for 4.3 years: 12 of the 91 patients (13.2%) who underwent surgical resection were diagnosed with invasive adenocarcinoma. In addition, of the 49 cases that changed to part‐solid nodules and underwent surgical resection, 12 were invasive adenocarcinomas (9 lepidic, 2 acinar, and 1 solid), 10 were MIA, and 10 were AIS.…”

Clinical, radiological, and pathological features of minute pulmonary meningothelial-like nodules and diffuse pulmonary meningotheliomatosis

“…DPM is a rare type of MPMN and was first reported by Suster et al in 2007 ( 5 ). We conducted a review of the literature through March 2023 for studies reporting cases of DPM by searching multiple scholarly databases ( 6 , 7 , 14 – 17 ). Of the 48 cases identified, only 5 were men (10.4 %), and 43 were women (89.6%).…”

“…It has been speculated to arise from the proliferation of MPMNs although the exact mechanism of transformation is not well understood. DPM typically presents with respiratory symptoms such as cough and shortness of breath, and it is more commonly discovered in women; many patients have a history of malignancy and are typically diagnosed by surgical lung biopsy ( 6 , 7 ). As a rare disease, there have been few research reports on DPM, and clinical doctors, radiologists, and pathologists have only limited understanding of DPM.…”