INTRODUCTION
Immunoglobulin G subclass 4 (IgG4)-related disease (IgG4-RD) is a relatively new and emerging immune-mediated disease with the prevalence of approximately 0.28 to 1.08 per 100,000 population.1Initially linked with autoimmune pancreatitis (AIP) this immune-mediated fibro-inflammatory condition, now virtually has been described in all organ system: biliary tree, salivary glands, periorbital tissues, kidneys, lungs, lymph nodes, meninges, aorta, breast, prostate, thyroid, pericardium and skin.2, 3 On histopathology, affected organ/tissue presents as tumor-like lesions with dense lymphoplasmacytic infiltrates enriched with IgG4 positive plasma cells, characteristic “storiform” fibrosis, obliterative phlebitis and increased eosinophils.4 Serum IgG4 level is elevated but is not a specific marker of the disease.5
IgG4-related sclerosing cholangitis (IgG4-SC) is the most common extrapancreatic manifestation of IgG4-RD. It affects the biliary tree which usually occurs along with autoimmune pancreatitis (AIP).3, 6 Clinically, they present as obstructive jaundice, and cholangiographic findings may suggest cholangiocarcinoma or primary sclerosing cholangitis. Presence of the hypermetabolic bile duct mass goes along with the cholangiocarcinoma. Clinical course, treatment and prognosis vary between these two, thus needs proper differentiation, though may be difficult.7 IgG4 responds to glucocorticoid therapy, whereas cholangiocarcinoma may need surgery with or without chemotherapy.8
Herein, we report a case of a male who presented with features of obstructive jaundice mimicking cholangiocarcinoma without the features of acute pancreatitis, and responded well to the steroid therapy.