IgG4-Related Kidney Disease With Pancreatic Mass and Protein-Losing Enteropathy: A Case Report

IgG4-related disease (IgG4-RD) is a fibroinflammatory condition characterized by tumefactive lesions, dense lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells.We report a 67-year-old male with a history of transient jaundice and recurrent steatorrhea, initially diagnosed at age 62. Abdominal MRI raised suspicion of pancreatic cancer due to a pancreatic head mass.The patient opted for conservative management, and jaundice resolved spontaneously.Diabetes was diagnosed concurrently.The patient was referred to our department for generalized edema of 3 months duration and elevated serum IgG4 at 67. Kidney biopsy confirmed IgG4-related kidney disease (IgG4-RKD) and diabetic nephropathy.Gastrointestinal endoscopy revealed multiple polyps, with IgG4-positive plasma cell infiltration in gastric and colonic tissues.Follow-up CT excluded pancreatic mass.After excluding systemic lupus erythematosus and plasma cell/lymphocytic proliferative disorders, the patient was treated with glucocorticoids and rituximab.Steatorrhea and edema improved, and serum IgG4 levels decreased.Urinary protein resolved, but hypoalbuminemia persisted.99mTc-HSA scintigraphy indicated intestinal protein loss.This case illustrates a significant treatment response in IgG4-RD involving the kidney, pancreas, and gastrointestinal tract, complicated by protein-losing enteropathy (PLE).Routine IgG4 testing should be considered in patients with unexplained kidney disease or tumefactive lesions.