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

Immunoglobulin G4 (IgG4)-related disease is a fibroinflammatory condition characterized by tumefactive lesions, dense lymphoplasmacytic infiltrates rich in IgG4-positive plasma cells. We report the case of a 67-year-old man with a history of transient jaundice and recurrent steatorrhea, initially diagnosed at 62 years. Abdominal magnetic resonance imaging raised suspicion of pancreatic cancer owing 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 an elevated serum IgG4 level at age 67. Kidney biopsy confirmed IgG4-related kidney disease and diabetic nephropathy. Gastrointestinal endoscopy revealed multiple polyps, with IgG4-positive plasma cell infiltration in gastric and colonic tissues. Follow-up computed tomography 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. Technetium-99m--labeled human serum albumin scintigraphy indicated intestinal protein loss. This case illustrates a significant treatment response in IgG4-related disease involving the kidney, pancreas, and gastrointestinal tract, complicated by protein-losing enteropathy. Routine IgG4 testing should be considered in patients with unexplained kidney disease or tumefactive lesions.