An adolescent girl with retarded development, delayed puberty, and hypergammaglobulinemia had anemia unresponsive to iron therapy that was cured when a mass of mediastinal giant lymph node hyperplasia was removed surgically. Rapid growth and development of secondary sexual characteristics occurred after operation. Follow-up studies made 20 years after operation showed compensated increased erythrocyte hemolysis and increased serum IgM. When mediastinal giant lymph node hyperplasia with abundant plasma cells is seen in childhood, there may be refractory anemia and immune disturbances. Similar giant lymph node hyperplasia without plasma cells may be found in an asymptomatic child or adult. The pertinent features of the few symptomatic cases reported are reviewed.