Case of IgG4-Related Disease Presenting With Dissecting Aneurysms in the Bilateral Internal Iliac Arteries After the Resolution of Periarteritis.

In this report, we present the case of an 83-year-old man diagnosed with IgG4-related disease (IgG4-RD) who developed dissecting aneurysms in the internal iliac arteries post-resolution of bilateral periarteritis. The patient initially presented with weight loss, anemia, and lymphadenopathy for over 13 years without a definitive diagnosis. Laboratory tests revealed elevated serum IgG4 levels and decreased complement levels, leading to a diagnosis of IgG4-RD. This was confirmed by a biopsy of the left axillary lymph node, which showed dense infiltration of IgG4-positive plasma cells. Contrast-enhanced CT revealed extensive periarterial soft tissue masses around the thoracic aorta, thoracic vertebrae, mediastinum, and internal iliac arteries, which were significantly reduced after the initiation of corticosteroid therapy with high dose prednisolone. Despite the initial improvement in clinical and radiological findings, the patient subsequently developed dissecting aneurysms in both internal iliac arteries. The right internal iliac artery aneurysm exhibited rapid enlargement, necessitating endovascular treatment with stent grafts to prevent rupture. This case highlights the complexity of vascular involvement in IgG4-RD, underscoring the need for careful monitoring even after apparent disease improvement. Although arterial wall thickening improves, the infiltration of IgG4-positive plasma cells persists indicating that the risks of aneurysm and arterial dissection remain. This is the sparsely reported case of bilateral dissecting aneurysms of the internal iliac arteries associated with IgG4-RD, providing new insights into the vascular manifestations and management of IgG4-RD.