Interstitial nephritis in a patient with atypical Sjögren's syndrome

A patient was observed with interstitial nephritis which resulted in renal tubular acidosis (distal type), tubular proteinuria and defective urinary concentrating ability in the absence of edema, elevated arterial blood pressure, glomerular proteinuria or abnormal urinary sediment. The presence of interstitial nephritis was established by renal biopsy which showed dense infiltrates in the interstitium, interstitial fibrosis and thickening and splitting of the pericapillary basal membranes. Immunofluorescence was non contributory. Extrarenal symptoms were discrete (arthralgia of both hands, Raynaud's syndrome upon cold exposure). Mixed connective tissue disease (MCTD) was suspected because of a positive ANF test (speckled pattern), which was completely abolished by ribonuclease pretreatment. However, in hemagglutination tests, no antibodies against ribonuclear protein (ENA) could be demonstrated. The diagnosis of Sjögren's syndrome was established by demonstration of antibodies against SSA and SSB antigens. The observation suggests that in patients with interstitial nephritis the diagnosis of Sjörgren's syndrome must be considered even if extrarenal symptoms of Sjögren's disease are minimal or lacking. The diagnosis can be established with recent serological techniques.