Metastatic Lung Adenocarcinoma Mimicking Meningioma.

A 54-year-old woman was admitted because of a lung mass on computed tomography (CT), which was identified as lung adenocarcinoma with multiple pulmonary metastasis and carcinomatous pleurisy. She was also found to have a brain tumor 5 cm in diameter on magnetic resonance imaging (MRI) 2 months before admission. The mass was heterogeneous on T2-weighted imaging with surrounding edema (Picture A). Post-contrast T1-weighted imaging showed a heterogeneously enhanced right parietal mass (Picture B) with thickening of the adjacent dura matter (arrows) on repeat MRI during admission, suggesting meningioma or metastasis to meningioma. Because of an exacerbated headache, stereotactic craniotomy was performed. A macroscopic examination revealed a mass in the cerebral parenchyma without dural adhesion or dissemination. A histological examination revealed papillary proliferation of columnar tumor cells (Picture C) with TTF-1 (Picture D) and Napsin A positivity, indicating metastasis of lung adenocarcinoma to the cerebral parenchyma. It can be difficult to distinguish brain metastases from meningiomas using standard neuroimaging techniques (1,2).

Picture.

The authors state that they have no Conflict of Interest (COI).