Case Presentation
A 52 years old male patient with a history of allergic rhinitis and not using any medication before evaluated. Serum urea 102.1mg/dl (12.84-42.8mg/dl), creatinine 4.66mg/dl (0.70-1.20mg/dl), eGFR 13 ml/min/1.73m2 (60-120 ml/min/1.73m2), serum albumin 30.4 gr/l (35-52 gr/l), blood eosinophil 1.23 10^3/µl (0.03 - 0.59 10^3/µl), C-reactive protein 69.8 mg/l (0-5 mg/l), 1+proteinuria in complete urinalysis, 1527.5 mg/day proteinuria in 24-hour urine, C3c 0.38 g/l (0.9-1.8 g/l), C4 <0.02 (0.1-0.4 g/l), serum amyloid A 50.70 mg/dl (5.7-8.2 mg/dl), IgG 37.83g /l (7-16g/l), α1 globulin 6% (2.9-4.9%), β1 globulin 3.2% (4.7-7.2), β2 globulin% in protein electrophoresis 7.8 (3.2-6.5), γ globulin 39.4% (11.1-18.8) were detected in laboratuary assessment. The patient’s liver and thyroid function tests and pancreatic enzymes were normal. There was no growth in the blood and urine cultures. Rheumatoid factor and autoantibody tests were negative in his examinations in our clinic. Contrast-enhanced abdominal computed tomography of the patient revealed an inflamed appearance in the adipose tissue in the left pararectal region, loss of corticomedullary separation and hypodense patchy areas in both kidneys detected (Figure 1 and 2). Contrast nephropathy, tubulointerstitial nephritis(TIN) or vasculitis considered in the differential diagnosis.
In the needle biopsy samples taken from the left pararectal region of the patient, mononuclear inflammatory cells infiltration rich with eosinophil leukocytes and plasma cells observed in fibrolipomatous tissues showing fibrosis. More than 10 IgG4-expressing plasma cells counted in 1 high magnification field in plasma cells that showed CD68 negative and CD138 positive staining. These histopathological findings found to be significant in terms of IgG4-RD.
The patient had normal kidney size and proteinuria over 1.5 g/day. Kidney biopsy performed. No endocapillary or extracapillary proliferative or necrotizing lesions observed in the biopsy. Intense fibrocollagenous connective tissue increase in the interstitium, and tubular atrophy, coarsening and wrinkling of the tubular basement membranes noted. Mononuclear cell infiltration rich with plasma cells observed. In the IgG4 staining, it was seen that the plasma cells stained positively in 16-20/ one large magnification. No significant vasculopathy, arteriolar concentric sclerosis or hyalinosis detected in the arteries.
Considering IgG4-related tubulointerstitial nephritis, 250mg/day intravenous prednisolone started for 3 days, followed by maintenance 0.5mg/kg/day oral prednisolone. Angiotensin converting enzyme and proton pump inhibitor, calcium+vitamin D was given. At the first follow-up after 15 days, the patient stated that his current complaints regressed dramatically. Laboratuary values found as serum urea 95.7mg/dl (12.84-42.8mg/dl), creatinine 1.96mg/dl (0.70-1.20mg/dl), and 24-hour urine protein 238.5mg/day (0-140mg/dl). The patient’s follow-up and treatment continue in our unit.