Radiological manifestations, histological features and surgical outcomes of pulmonary meningothelial proliferation: a case series and rethinking

Abstract

Background: Lung cancer screening with computed tomography (CT) has been adopted worldwide. Consequently, there is an increase of some previously rarely reported lesions, like pleuropulmonary meningothelial proliferation (PMP), which included metastatic pulmonary meningiomas (MPMs), primary pulmonary meningiomas (PPMs) and minute pulmonary meningothelial-like nodules (MPMNs). To date, the understanding of the clinical management of PMP is limited.

Methods: We retrospectively searched PMP (MPMs, PPMs, and MPMNs) on the medical database (May 2005 to April 2019) of our department, and extracted the demographic and perioperative information. The last follow-up was in May 2019.

Results: A total of 78 patients, including 16 (20.5%) males and 62 (79.5%) females, were enrolled, with the median age as 61 (range, 27-78) years. There was 1 case with multiple MPMs, 4 cases with PPMs and 73 cases with MPMNs. On CT, MPMs manifested as round nodules with solid or part-solid components. PPM mainly presented as an isolated, round, solid, and well-circumscribed nodule, with or without lobulation. While MPMNs often showed as multiple, round, randomly-distributed, solid or partly-solid nodules, most of which were in tiny size. Histologically, MPM, PPM, and MPMN had similar morphological and immunohistochemical (IHC) features. As to the surgical outcomes, the case with multiple MPMs had undergone a progression after wedge resection and was in an active monitoring. And the four cases with PPMs and the five cases with MPMNs were all in regular surveillance.

Conclusions: PPM has variable radiological manifestations. But it can be histologically identified by the characteristic features. Although surgery is able to achieve satisfying prognosis, active observation is an alternative in selected cases due to the surgical invasiveness and the indolent nature of the disease.

Keywords: Pulmonary meningothelial proliferation; histology; radiology; surgery.

Figure 1

MPMs on positron emission tomography with or without CT. (A) the pulmonary nodule in the right lower lobe at the first detection; (B) the smaller nodules in bilateral lobes; (C) the metabolic uptake of the mediastinal mass; (D) the increasement of the nodule in the right lower lobe after 7-year’ surveillance; (E) the increasement of the mediastinal mass after 7-year’ surveillance. Arrows: the smaller nodules in bilateral lobes. MPMs, metastatic pulmonary meningiomas; CT, computed tomography.

Figure 2

Histological features of MPMs. (A) Macroscopically, MPMs showed as spindle cells arranged in swirls on hematoxylin-eosin staining (×200); (B,C,D) immunohistochemically, metastatic pulmonary meningioma showed positive for Vimentin (×100), EMA (×200), PR (×200). MPMs, metastatic pulmonary meningiomas.

Figure 3

PPMs on CT. (A,B) PPMs showing as isolated, round, solid, and well-circumscribed nodules, with or without lobulation. PPMs, primary pulmonary meningiomas; CT, computed tomography.

Figure 4

Histological features of PPMs. (A) Macroscopically, PPMs showed as spindle cells organized in bundles and whorls on hematoxylin-eosin staining (×200); (B,C,D) immunohistochemically, primary pulmonary meningioma showed positive for Vimentin (×100), EMA (×200), PR (×200). PPMs, primary pulmonary meningiomas.

Figure 5

MPMNs on CT. (A,B,C) MPMNs showing as GGOs with or without mixed components, (D) or as solid nodules. Arrows: the small nodules in pulmonary lobes. MPMNs, minute pulmonary meningothelial-like nodules; CT, computed tomography; GGOs, ground-glass opacities.

Figure 6

Histological features of MPMNs. (A) Macroscopically, MPMNs showed as some spindle-shaped cells on hematoxylin-eosin staining (×200); (B,C,D) immunohistochemically, MPMNs showed positive for Vimentin (×100), EMA (×200), PR (×200). MPMNs, minute pulmonary meningothelial-like nodules.

Figure 7

Surveillance periods before and after surgery of the one case with MPM, the four cases with PPMs, and the five cases with MPMNs (with no lung cancer-related lesions). MPM, metastatic pulmonary meningioma; PPMs, primary pulmonary meningiomas; MPMNs, minute pulmonary meningothelial-like nodules.