#Polyneuropathy

#CHIP #Clonalhematopoiesisofindeterminatepotential

#Autoimmune

#Vascularparkinsonism

#MisdiagnosisinSUD

#HFPEF

#pyuria

#DDXNeckpaindysphagia

#Infectionsthrombocytopenia

IGG-4 RELATED DISEASE WHAT? • A chronic, immune-mediated fibroinflammatory disease with tumefactive infiltration of IgG4+ plasma cells and lymphocytes. • Characterized by: - Storiform fibrosis - Organ inflammation - Organ enlargement - Organ dysfunction PATHOPHYSIOLOGY • Immune basis: Th2 & Treg cell-mediated • Key Features: - Tumefactive lesions - IgG4+ plasma cell infiltration - Storiform fibrosis - Obliterative phlebitis - Chronic inflammation -> progressive organ dysfunction • Serum IgG4 elevated in ~70% (not specific) COMMON CLINICAL PRESENTATIONS (BY ORGAN) • Pancreas: Type 1 AIP (Autoimmune Pancreatitis), mass effect, painless jaundice; mass: "sausage shaped" pancreas • Biliary Tract: IgG4-Sclerosing Cholangitis - mimics PSC; often with AIP • Salivary/Lacrimal Glands: Mikulicz disease (bilateral swelling), Küttner tumor (Submandibular glands), dacryoadenitis • Orbit: Dacryoadenitis, orbital pseudotumor, proptosis • Retroperitoneum: Retroperitoneal fibrosis (Ormond disease); may obstruct ureters • Aorta: Inflammatory aortitis, mimics vasculitis • Kidneys: Tubulointerstitial nephritis (TIN), membranous nephropathy, proteinuria • Lungs: Nodules, interstitial changes • Hypertrophic pachymeningitis: Dura mater (intracranial/meninges) • Lymphocytic hypophysitis: Pituitary gland • Others: Thyroid (Riedel's), CNS, prostate, breast, skin DIAGNOSIS • Essential Criteria: Clinical/radiologic evidence of mass or organ enlargement • Histopathology: - Dense lymphoplasmacytic infiltrate - 30-50 IgG4+ plasma cells/HPF - Storiform fibrosis - Obliterative phlebitis • Exclusion of Mimics: Infectious, malignant, or other autoimmune diseases • Supportive Labs: - ↑ Serum IgG4 (~66%) - not specific - ↑ IgE, ↓ complement • Classification: 2019 ACR/EULAR Criteria (>= 20 points): stepwise approach with mimics excluded MANAGEMENT • First-Line: - Prednisone: 0.6 mg/kg/day, tapered over 2 months • Refractory or Steroid-Dependent: - Rituximab: 1 g IV x2 doses, 2 weeks apart - Inebilizumab: 300 mg IV x2 doses • Other options: - Azathioprine: 2 mg/kg/day - Mycophenolate mofetil: 2-2.5 g/day #IGG-4 #IGG4 #Diagnosis #Management #Rheumatology