IgG4-Related Disease Clinical history: Man, 60 years, multiorgan involvement, unique or multiple inflammatory pseudotumor 4 phenotypes: • Pancreato-hépato-biliary • Retroperitoneum and aorta • Head and neck-limited (orbital, extraocular muscle, sinusitis, parotid gland, submandibular gland, lacrimal gland), female, asian • Systemic (head and neck, pancreas, biliary, renal, lung, lymph node), high serum IgG4 concentration PET-CT Imaging (→ Diagnostic orientation, Biopsy orientation): • More sensitive than conventional imaging (aorta, salivary glands, lymph nodes) • Some false negative (small lesions, meninges, kidneys) • Strong correlation with response to treatment and relapse No specific laboratory tests: • IgG4 : nonspecific, absent in 10-30% • Polyclonal hypergammaglobulinemia, ↑ acute phase reactants, eosinophilia, ↑ serum lgE, no autoantibodies (antinuclear antibodies, rheumatoid factor), ± hypocomplementemia Histology - Non-specific: • No necrosis, No vasculitis, No granuloma, No monoclonality • "Reactive lymphoid hyperplasia with increased IgG4+ cells" Treatment: • Glucocorticoids (0.6 mg/kg/day) - Relapse >40% supporting long-term maintenance with GCs GC-dependency • No response to glucocorticoids - reconsider diagnosis (new biopsy+++) • 2nd line: No consensus but rituximab more widely used than azathioprine, cyclophosphamide, methotrexate,... By Dr. Camille Mettler @Mettler_K1000 #IgG4 #Related #Disease #diagnosis #management #phenotypes #workup #treatment #rheumatology
