Association of NK-cell lymphoproliferative disease and nephrotic syndrome.

A 56-year-old white man with a seven-year history of lymphocytosis of large granular lymphocytes (LGL) developed mild renal insufficiency (serum creatinine 150 mumol/L (1.7 mg/dL) with proteinuria (3.4 g/day). Laboratory investigations confirmed a proliferative disease of non-T lineage cytotoxic LGL/natural killer (NK) cells, and the renal biopsy documented focal and segmental glomerulosclerosis associated with interstitial inflammation and tubular atrophy. These findings could be explained by production and release of humoral mediators by pathologic LGL/NK cells. The renal function must be carefully monitored in patients with LGL/NK proliferative disorders, and the role of the NK cell system in renal diseases should be investigated.