IgG4-related disease — SCE Rheumatology MCQ

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EasyConnective tissue diseasesIgG4-related diseaseSCE Rheumatology

A 62-year-old man presents with painless bilateral submandibular gland enlargement and obstructive jaundice. Serum IgG4 is markedly elevated. CT shows diffuse, sausage-shaped enlargement of the pancreas with a capsule-like rim and narrowing of the distal common bile duct. What is the most likely diagnosis?

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Correct answer: C — IgG4-related disease

The correct answer is **IgG4-related disease**. Painless submandibular enlargement, markedly elevated serum IgG4 and diffuse sausage-shaped pancreatic enlargement with a capsule-like rim indicate IgG4-related sialadenitis with type 1 autoimmune pancreatitis; biliary involvement explains the obstructive jaundice. Pancreatic adenocarcinoma is an important mimic but more commonly produces a focal pancreatic mass and does not account for the characteristic bilateral salivary-gland disease. Primary Sjögren syndrome typically causes sicca symptoms and does not characteristically cause type 1 autoimmune pancreatitis. ANCA-associated vasculitis and sarcoidosis can be multisystem disorders but do not fit this pancreatic imaging and serological pattern. In clinical practice, serum IgG4 is not diagnostic in isolation, and tissue sampling may be required to exclude malignancy before treatment.

Reference: Wallace ZS et al. The 2019 American College of Rheumatology/European League Against Rheumatism classification criteria for IgG4-related disease. Ann Rheum Dis. 2020;79:77–87. https://pubmed.ncbi.nlm.nih.gov/31796497/