A case report: an unusual case of ulcerative intestinal IgG4-related disease with clinical features overlapping with probable intestinal Behcet’s disease

Abstract Background IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory condition characterized by IgG4-positive plasma cell infiltration, typically presenting with organ enlargement or tumor-like masses. Luminal gastrointestinal involvement is rare, and ulcerative lesions are even less common. Overlap syndromes of IgG4-RD with other immune disorders have been reported, but overlap of its clinical features with those of intestinal Behcet’s disease has not been documented. Case presentation A 62-year-old man with a history of recurrent oral ulcers presented with sudden hematochezia and hypovolemic shock. Imaging revealed sclerosing mesenteritis, and endoscopy identified multiple small intestinal ulcers. Histopathological examination of the resected intestinal segment demonstrated dense infiltration of IgG4-positive plasma cells (70/HPF, IgG4⁺/IgG⁺ ratio 42.3%), confirming intestinal IgG4-RD. The patient also met diagnostic criteria for probable intestinal Behcet’s disease based on recurrent oral ulcers, crateriform intestinal ulcers, and histologic evidence of vasculitis. Following partial enterectomy and postoperative immunosuppressive therapy (prednisone and cyclophosphamide), the patient achieved sustained remission with no recurrence during the one-year follow-up. Conclusions This is the first reported case of concurrent intestinal IgG4-RD and probable intestinal Behcet’s disease. The overlapping presentation expands the clinical spectrum of IgG4-RD and suggests a potential pathogenic link between these two immune-mediated conditions.