Back
Granulomatous tubulointerstitial nephritis (GTIN) is a rare entity, comprising less than 1% of all renal biopsies. Its etiology is broad, including systemic inflammatory disorders such as granulomatosis with polyangiitis (GPA), sarcoidosis, Crohn's disease, Sjögren's syndrome (SS), malignant neoplasms (chronic lymphocytic leukemia), and infections by fungi and mycobacteria. Additionally, various antibiotics, including beta-lactams, have been associated. Distinguishing between these etiologies based solely on renal histology is challenging, often requiring consideration of clinical presentation and extrarenal findings. Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by lymphocytic and plasmacytic infiltration of exocrine glands. Renal involvement varies, ranging from glomerular (cryoglobulinemic glomerulonephritis) to tubular (tubulointerstitial nephritis, distal and proximal tubular acidosis with Fanconi syndrome), with the latter being more common. We present this case due to the uncommon manifestation of Sjögren's syndrome
A 36-year-old woman with a history of chronic kidney disease (CKD) presented with acute otitis media, treated with amoxicillin-clavulanate. Subsequently, she developed abdominal pain, diarrhea, and oral intolerance. Laboratory results showed anemia, eosinophilia, elevated urea, and creatinine. Arterial blood gas revealed metabolic acidosis. Urinalysis indicated proteinuria, hematuria, and dysmorphic red blood cells. Serological tests revealed positive anti-nuclear antibodies (ANA) and negative anti-DNA antibodies. Renal biopsy was performed.
Renal biopsy revealed granulomas with well-defined borders, lymphoplasmacytic infiltration, and extensive tubular atrophy (70%). Immunofluorescence and electron microscopy were negative for deposits. The final diagnosis was chronic granulomatous tubulointerstitial nephritis secondary to primary Sjögren's syndrome.
Chronic kidney disease due to tubulointerstitial nephritis is the most common renal manifestation in pSS. While lymphocytic-mononuclear infiltration is typical, the formation of granulomas is atypical, with few reported cases. There is no consensus on the treatment of renal damage in pSS, but immunosuppressive agents such as corticosteroids, mycophenolate, and rituximab are used based on lesion extent and nature. Early diagnosis is crucial for favorable outcomes. The presented case also highlights beta-lactams as a potential underlying cause of granulomatous interstitial nephritis, ruled out due to recent drug exposure and the advanced tubulointerstitial lesions indicating a longer evolution time (70% atrophy and fibrosis).