[Renal involvement in Sjögren's syndrome--interstitial nephritis and glomerulonephritis]

Renal involvement is well recognized extraglandular manifestation of primary Sjögren's syndrome (SS). The most common histopathological lesion is an interstitial lymphocytic infiltrate with tubular atrophy and fibrosis. The clinical presentation may be hyposthenuria, overt or latent distal renal tubular acidosis and less commonly Fanconi's syndrome. These tubular dysfunctions correlate with the presence of interstitial lymphocytes. Immunoregulatory alterations consisting of impaired T-cell function and B-cell hyperactivity probably play a pathogenetic role in the development of interstitial nephritis in SS. Glomerulonephritis in SS has been described in a limited number of case reports. Variant modes of pathogenesis have been proposed in these cases where glomerulonephritis has been associated with immune complex deposition and cryoglobulinemia.