IgG4 related interstitial nephritis: A case report and review of literature
A 39-year-old man was referred for evaluation of renal failure. He complained of weight loss of about 8 kg and intermittent fever during the previous 3 months. There was no history of dry mouth or eyes. Examination revealed cervical, axillary and inguinal lymphadenopathy, bilateral parotid enlargement, and hepatosplenomegaly. There was trace ankle edema. Blood pressure was 140/90 mmHg. Examination of heart, lung, and nervous system revealed no abnormalities. Investigations: Urine analysis-trace proteinuria, spot urine protein-creatinine ratio: 0.53, no active sediments. Blood: Hemoglobin 11.8 g/dl; Total count 7800/mm3 (polymorphs 64%, lymphocytes 27%, monocytes 2%, eosinophils 7%), erythrocyte sedimentation rate 64 mm-1st h, peripheral smear revealed no abnormal immature white blood cells. Urea 56 mg/dl; creatinine 2.4 mg/dl; sodium 134 mEq/L, potassium 3.8 mEq/L, total serum protein 8.6 g/dl, albumin 3 g/dl, globulin 5.6 g/dl, serum transaminases were within the normal limits. Serology for HIV, HBsAg, and anti-HCV antibody were negative. Ultrasonogram of abdomen revealed large kidneys (right-18.2 × 7.2 cm; left-18.4 × 7.4 cm). CT abdomen confirmed the ultrasound findings, and no abnormalities were noted in pancreas. Renal biopsy: light microscopic examination revealed massive interstitial infiltration of lymphocytes, plasma cells, and a significant number of eosinophils with extensive fibrosis and tubular atrophy. Glomeruli were normal. Immunofluorescence for IgG showed intense positivity in the capillary walls. Stains for IgM, IgA, C3, C4, C1q, Kappa, and Lambda light chains were negative. Immunohistochemical stain for IgG4 was diffusely positive with most of the cells showing positivity (more than 50 cells/hpf) [Figures –].