Arterial and Venous Thrombosis as the First Manifestation of IgG4-Related Disease: A Case Report

Background IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disorder that can mimic malignancy and autoimmune conditions. Vascular involvement is uncommon, and simultaneous arterial and venous thrombosis as an initial presentation is exceptionally rare. Case presentation: We report a 47-year-old woman who presented with acute left lower limb ischemia secondary to popliteal artery thrombosis, accompanied by superior mesenteric vein thrombosis. Despite urgent thrombectomy and therapeutic anticoagulation, she developed recurrent arterial occlusion and bowel ischemia requiring small bowel resection. Laboratory evaluation revealed a normal thrombophilia panel, negative ANA and ENA, mildly elevated C-reactive protein, and reduced IgG subclasses. Histopathological examination of the resected bowel demonstrated storiform fibrosis and dense lymphoplasmacytic infiltration with more than 10 IgG4-positive plasma cells per high-power field, confirming the diagnosis of IgG4-RD. She showed clinical stabilization following high-dose intravenous methylprednisolone followed by oral glucocorticoids. Conclusion This case illustrates an unusual presentation of IgG4-RD with concurrent arterial and venous thrombosis. Early recognition of this atypical manifestation is critical, as timely diagnosis and glucocorticoid therapy may prevent irreversible organ damage.