IgG4-Related Disease — RACP Adult Medicine MCQ

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HardRheumatologyIgG4-Related DiseaseRACP Adult Medicine

A 55-year-old man presents with bilateral parotid and lacrimal gland enlargement, retroperitoneal fibrosis, and autoimmune pancreatitis. Serum IgG4 is markedly elevated (8.5 g/L, normal <1.4). Tissue biopsy shows storiform fibrosis with dense IgG4-positive plasma cell infiltrate. What is the most likely diagnosis?

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Correct answer: E — IgG4-related disease

Multi-organ involvement (salivary/lacrimal glands, pancreas, retroperitoneum) with markedly elevated serum IgG4 and characteristic tissue findings (storiform fibrosis, obliterative phlebitis, dense IgG4+ plasma cells) is IgG4-related disease. It responds dramatically to corticosteroids. Rituximab is used for relapsing or refractory disease. Pancreatic involvement may mimic pancreatic cancer.

Reference: ACR/EULAR – 2019 – IgG4-RD Classification; GESA 2024