Urticaria with immunoglobulin G4-related disease: An association or coincidence?

Immunoglobulin (Ig) G4-related disease is a recently described fibro-inflammatory disease with diverse clinical manifestations but consistent and characteristic histopathological features across multiple organ systems and skin, leading to tissue sclerosis and ultimately organ failure if not treated adequately. Here, we report a case of 56-year-old male patient presenting with urticarial lesions and generalized itching for 4 months. Routine investigations showed elevated 24-h urine protein, absolute eosinophil count, serum IgE, reversed albumin: globulin ratio, and “M” spike on serum electrophoresis. Renal biopsy showed storiform fibrosis, diffuse dense inflammatory cells (plasma cells and eosinophils), and IgG4-positive cells on immunohistochemistry which was histologically highly suggestive of IgG4-related chronic tubulointerstitial nephritis. Quick response was seen with oral corticosteroids.