Primary Pulmonary Meningioma Presenting as a Coin Lesion.

The patient was a 44-year-old asymptomatic man with a round nodule observed in the left lung on a chest X-ray (Picture A, arrow). Chest computed tomography revealed a well-circumscribed mass in the peripheral apico-posterior segment (Picture B). A gross examination of the partially resected lung revealed a 2.0×2.0×1.8 cm, well-demarcated, tan-colored, solid tumor (Picture C). Histopathologically, the tumor was composed of spindle cells arranged in fascicular or whorl fashion interspersed with collagens and psammomatous calcifications (Picture D). Immunohistochemically, the tumor cells exhibited immunoreactivity for vimentin, EMA, progesterone receptor, and claudin-1 (Picture D, inset). Magnetic resonance imaging revealed no cranial/spinal tumor. Thus, the tumor was diagnosed as primary pulmonary meningioma (PPM).

Picture.

PPM is exceedingly rare but is now categorized as a distinct entity in the latest WHO classification of lung tumors, 2015. PPMs are nearly always benign (1). Worryingly, a high-uptake on fluorodeoxyglucose (FDG)-positron emission tomography (PET) is a feature of PPMs (2), which mimics malignancy and can lead to a misdiagnosis and overtreatment.

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