IgG4 Related Disease as a Differential Diagnosis in Multi-Organ Systemic Disease

IgG4 related disease is a relatively recently recognized systemic entity, that has been observed in nearly every organ system, with similar histopathological features across all identified organs. IgG4 is an antibody molecule accounting for less than 5% of the total IgG count in a healthy person. The molecule is implicated in numerous autoimmune diseases;however its role in IgG4 related disease, whether primary or secondary, remains unknown. The gold standard in the diagnosis of this condition is demonstration of organ involvement from biopsy specimens. In this case report, the patient had exhibited symptoms related mainly to the gastrointestinal tract for 12 years prior to his diagnosis of IgG4 related disease. After this patient’s diagnosis of IgG4 related disease, he was commenced on Rituximab, a monoclonal antibody, which was successful in subsiding his symptoms and he has remained symptom free for the past two years of follow up since commencing treatment and hadn’t developed any complications of the disease nor any complications related to treatment. IgG4 related disease is a systemic autoimmune disease that involves multiple organs 60% - 90% of the time, therefore clinicians should be aware that IgG4 related disease can mimic some autoimmune rheumatic diseases and place it as a differential diagnosis when multi-organ disease with systemic features is involved.

A Case of Acute Renal Failure Associated with IgG4-Related Disease Presenting Both Tubulointerstitial Nephritis and Retroperitoneal Fibrosis

We report a case of IgG4-related disease presenting both tubulointerstitial nephritis and retroperitoneal fibrosis causing acute renal failure in a 63-year-old male. He was admitted to our hospital because of acute renal failure requiring emergent hemodialysis. Computed tomography showed a soft-tissue density mass with an irregular border in the retroperitoneum. The mass involved bilateral ureters and had caused acute renal failure by bilateral hydronephrosis. Because of a history of uveitis and high IgG4 levels, we considered a diagnosis of retroperitoneal fibrosis, IgG4-related disease. Kidney biopsy revealed IgG4-related kidney disease with interstitial nephritis. After relief of urinary obstruction by inserting ureteral catheters into the bilateral ureters, renal function recovered.

Cholangiocarcinoma, Primary Sclerosing Cholangitis, or IgG4-Sclerosing Cholangitis: Similar Presentations with Different Managements

In our case, we present a case of an 80-year-old male who was referred to the gastroenterologist for evaluation of a suspicious mass. CT imaging at the time had shown intrahepatic and extrahepatic biliary dilations, and the patient was thought to have a pancreatic or a common bile duct mass. A mass biopsy showed no malignancy, and further evaluation was warranted. The patient was found to have elevated IgG4 levels and was diagnosed with IgG4-sclerosing cholangitis (IgG4-SC). IgG4 has been found to create a wide array of pathologies, including autoimmune pancreatitis, dacryoadenitis, and sialadenitis. These pathologies have been grouped under an IgG4-Related Disease (IgG4-RD) category. In some cases, this IgG4-RD can present as a subclass of primary sclerosing cholangitis due to immune depositions and swelling of the CBD. Due to the strictures caused by the sclerosing cholangitis, intrahepatic and extrahepatic dilations might be found on endoscopic ultrasound (EUS). It is imperative to differentiate this from a malignant mass as the early recognition and treatment of IgG4-SC can lead to complete resolution. In this case report, we present a case of a patient who was found to have IgG4-SC and responded well to steroid treatment.