Primary Sjӧgren's syndrome with renal Fanconi syndrome: Good responses to treatment with glucocorticoids

Background Renal Fanconi syndrome (FS) is rare in primary Sjӧgren's syndrome (pSS). We aimed to describe the clinicopathological characteristics of pSS associated FS (pSS-FS) and its responses to treatment. Methods We reported 25 cases of pSS-FS patients and retrospectively reviewed their clinical records, kidney pathology and follow-up data. Results The 25 pSS-FS patients were mainly female (92.0%) and the mean age at diagnosis was 43.6±11.3 years. They showed different degrees of proximal tubular dysfunctions and eGFR decline (60.9±32.3 ml/min/1.73m2). Kidney pathology of pSS-FS patients showed tubulo-interstitial nephritis with defective brush border and lymphoplasmacytic infiltrates. After glucocorticoid treatment, the eGFR levels were significantly improved from 48.3±20.6 ml/min/1.73m2 to 55.0±19.9 ml/min/1.73m2 (P = 0.012) at the third month of follow-up. They also acquired good tubular (88.2%) and immunological (90.0%) responses. pSS-FS patients with young-onset pSS presented with a higher prevalence of positive anti-SSB antibody and hypocomplementemia, more severe hypokalemia, and better eGFR levels. Conclusions In pSS-FS patients, use of glucocorticoids could improve eGFR and tubular functions. The young-onset pSS group presented with a particular pattern in immunological features and kidney involvement.