Brief report

Immunoglobulin G4–related inflammatory pseudotumor of the stomach

Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease characterized by chronic fibrosing inflammation with abundant IgG4-positive plasma cells, and responds well to steroids. Previous reports of IgG4-RD have focused on pancreatic and extrapancreatic including the gastrointestinal tract, however, the colonic IgG4-RD is rare.

We herein report the case of a 74-year-old female with edematous wall thickening of the terminal ileum to the lower ascending colon confirmed by several preoperative imaging studies, who underwent right hemi-colectomy for suspected malignant lymphoma. The resected specimen showed an irregular wall thickness with subserosal sclerosis, and the lesion was 10 cm in length from the terminal ileum to the ascending colon. The patient was diagnosed with IgG4-RD by pathological examinations, which demonstrated an increased number of IgG4-positive plasma cells (150/HPF), and an elevated IgG4/IgG ratio (50%).

Gastrointestinal IgG4-RD appears to be difficult to diagnose prior to surgical resection because of its rarity, and the similarity of its features to malignancy.

The measurement of the serum IgG4 levels, immunohistochemical examination of biopsy specimens and use of several imaging modalities might help us to diagnose the disease without surgical resection, and this disease can generally be treated with steroid therapy. However, surgical resection for IgG4-RD may still be also necessary for patients with concerns regarding malignancy or with intractable gastrointestinal obstruction caused by this disease.

Gastrointestinal IgG4-RD often mimics malignancy, and we should therefore consider this disease in the differential diagnosis of colonic lesions in order to optimize the treatment.