Is primary pulmonary meningioma a giant form of a meningothelial-like nodule? A case report and review of the literature

Abstract

Minute pulmonary meningothelial-like nodules (PMNs) are asymptomatic, small nodules that are occasionally detected in surgical or autopsy specimens. Recent improvements in tumor imaging and the increased use of computed tomography (CT) scans of the chest have led to the early detection of these pulmonary nodules in various clinical settings, often before surgery or health examinations. However, large PMNs have rarely been observed. In this study, we report a patient with a large PMN, which was almost identical to so-called 'primary pulmonary meningioma'. A CT scan of his chest revealed a small, well-circumscribed nodule. Immunohistochemical analysis of the tumor revealed that the tumor cells were positive for CD56, epithelial membrane antigen, and progesterone receptor. Given the similarity of these results to the staining pattern of minute PMNs in previous reports, we suggest that the primary pulmonary meningiomas reported to date are, in fact, a giant form of PMN.

Keywords: CD56; Primary pulmonary meningioma; Pulmonary meningothelial-like nodule.

Fig. 1

Chest CT revealing a pulmonary nodule (white arrows) before surgery (a). In subsequent CT scans taken after 1 year (b) and 2 years (c), the nodule slightly increased in size.

Fig. 2

Surgical specimen showing a well-circumscribed, tan-white nodule (a). H&E staining showing that the nodule is well circumscribed (b), and contains cytologically bland, rounded, and spindled cells when examined under high-power magnification (c). Scattered psammoma bodies are noted (d).

Fig. 3

High-power magnification of immunohistochemical analysis of a tumor specimen of the left lung nodule. The tumor was positive for CD56 (a), weakly positive for EMA (b), positive for PR (c), and the Ki-67 labeling index was 4% (d).