Lymphoplasmacyte-rich meningioma: A rare histologic variant of benign meningioma with atypical bone invasion.

Meningiomas are the most common primary intracranial brain tumor and have been divided into 15 histologic subtypes, which are further classified into 3 grades according to biological behavior. Lymphoplasmacyte-rich meningioma is a rare histologic subtype of benign (grade 1) meningiomas characterized by prominent infiltration of plasma cells and lymphocytes, with a variable proportion of meningothelial elements. These benign meningioma variants usually cause significant peritumoral brain edema and mimic higher-grade lesions, which is believed to represent inflammatory cell infiltration rather than true neoplastic invasion. Bone invasion in these tumors is exceedingly rare and its clinical significance remains elusive. We describe the case of a lymphoplasmacyte-rich meningioma with skull invasion and peritumoral brain edema in a 57-year-old female patient presenting with left hemiparesis. Gross total resection of the lesion and adjacent skull were performed and histophatological examination disclosed a lymphoplasmacyte-rich meningioma. Gradual decrease of the parenchymal edema was seen on postoperative imaging studies and the patient showed progressive improvement of the motor deficit. This case report depicts rare bone invasion by lymphoplasmacyte-rich meningioma and highlights the other imaging features of this rare histologic subtype of benign meningioma. Due to the paucity of cases, gross total resection, and long-term follow-up are warranted as the prognosis of these tumors is still not fully understood.