Castleman's disease with renal infiltration by polyclonal plasma cells

A 52-year-old man was admitted to hospital because of declining renal function. Some months previously, biopsy from a mediastinal lymph node had shown Castleman's disease (angiofollicular lymph node hyperplasia). By now, a renal biopsy showed massive interstitial infiltration of predominantly plasma cells without significant atypia. On immunostaining, the plasma cells showed cytoplasmic reaction for IgG and kappa and lambda light chains, which had also been the case with the mediastinal lymph node. These findings were interpreted as interstitial renal involvement of Castleman's disease. The patient was treated with prednisone, upon which the renal function was stabilized, but not improved. The attention is drawn to Castleman's disease as a possible, although rare, cause of renal interstitial cellular infiltration.