Seven young patients ranging in age from 8 to 19 years had surgically removed meningeal neoplasms with a peculiar myxoid-chordoid pattern. The tumors were surrounded by massive polyclonal lymphoplasmacellular infiltrates with follicles and germinal centers. The patients preoperatively manifested iron-resistant hypochromic microcytic anemia, and one of them had dysgammaglobulinemia and stunted growth. After the masses were removed, the blood picture of the patients normalized, and the adolescent with retarded somatic development resumed normal growth, but two patients developed local recurrence with identical histology and again became anemic. It appears that the peritumoral lymphoplasmacellular infiltrates, which in these instances may be regarded as reactive rather than primary cell proliferations, nevertheless brought about the type of systemic manifestations known as the Castleman syndrome, characteristically seen in patients with angiofollicular lymphoid hyperplasia (hamartoma) of soft tissues, or Castleman's tumor. In one of our patients the inflammatory infiltrate extended far into the surroundings of the meningioma, resulting in the erroneous initial diagnosis of "encephalitis" from a needle biopsy of the brain near the tumor.