Meningioma With Tyrosine-Rich Crystalloids: A Case Report and Review of the Literature.

We report a case of fibrous meningioma with tyrosine-rich crystalloid in the frontal lobe of a middle-aged woman. The patient presented with a history of several years of worsening headaches and blurry vision, which progressed to include syncopal episodes and right-sided weakness. Imaging demonstrated a dural-based extra-axial mass arising from the right orbital roof and extending superiorly along the right frontal convexity causing right-to-left midline shift. The patient underwent a craniotomy and operative resection. Tumor architecture and cytology was similar to that of a Schwannian neoplasm, with spindled cells arranged in a fascicular architecture and displaying focal nuclear palisading. Immunohistochemical stains confirmed a diagnosis of fibrous meningioma. Light microscopy demonstrated extracellular deposits of eosinophilic crystalline material parallel to the spindled tumor cells, reminiscent of "tyrosine-rich" crystals described in salivary gland neoplasms. This is the third meningioma featuring tyrosine-rich crystalloid reported in the literature; we also summarize the previous 2 reports.