A rare case of chordoid meningioma in the lateral ventricle observed in an adult is reported. The first clinical manifestation of the disease was a prolonged fever of unknown origin. Abnormalities in the patient's blood chemistry, principally polyclonal hypergammaglobulinemia (immunoglobulin [Ig]G, IgA, and markedly IgE) and an elevated serum level of C-reactive protein, were associated with the disease. The tumor was histologically confirmed to be a chordoid meningioma, and its surgical removal resulted in complete resolution of the patient's symptoms. By combining reverse transcription-polymerase chain reaction and immunohistochemical analysis, it may be shown that cytokine production, including that of interleukin (IL)-6, IL-1beta, and vascular endothelial growth factor, plays a role in the pathogenesis of chordoid meningioma associated with Castleman syndrome.