2740 IgG₄-Related Disease: A Gastric Mass With an IgG4 Surprise

Abstract

INTRODUCTION: IgG₄-related disease is a rare autoimmune syndrome that causes fibrosis of glands, most commonly of the pancreas and biliary tract1,3. The overall prevalence is unknown, with an estimated less than 1:100,000 of the general population typically found in middle-aged males2,3. Diagnosis is made with IgG₄ levels at least 2x the upper limit of normal and dense lymphoplasmacytic infiltrate, however, it may be seen with normal IgG₄ levels6. Although rare, it can present similar to GI malignancies and should be considered in the differential for patients with autoimmune disease1,3,4,5. Here we present one of those unusual cases. CASE DESCRIPTION/METHODS: A 65-year-old lady with PMH of DM2 and Sjogren's Syndrome (SS) who presented to the hospital with intractable nausea, vomiting, and failure to thrive for over 1 month. The physical exam, labs that included CMP, LFTs, and serology was unremarkable; previous EGD revealed diffuse thickening of the gastric submucosa. Biopsy via open gastrectomy revealed chronic inflammation with multiple IgG₄ plasma cells and no signs of lymphoma, suspicious for IgG₄-RD. After the partial gastrectomy, serum Na levels were 162, which improved with DDAVP and was later confirmed to be diabetes insipidus (DI). Further workup and imaging were negative and baseline IgG and IgG₄ levels were 1178 and 61, respectively. Treatment included steroid therapy and DDAVP which improved her symptoms and preceded an uneventful hospital course. DISCUSSION: IgG₄-RD is a disease with numerous presentations based on the organs involved. It presents as a GI-specific illness due to its affinity for the pancreas and biliary tract1,2,3. As seen in our patient, although rare, it may also affect the stomach, form mass lesions and cause symptomatology similar to a GI malignancy3,5. In patients with autoimmune diseases, where GI malignancy is considered, it is reasonable to include IgG₄-RD in the differential. IgG₄-RD may mimic symptoms of SS, and therefore case-patients with SS should also be considered for IgG₄-RD. This patient also experienced DI which may be a manifestation of IgG₄-RD, as the syndrome may affect the pituitary4. This case is one of the few instances reported to have pituitary involvement after the onset of multiorgan involvement4. Like other autoimmune disorders, IgG₄-RD is responsive to steroid therapy or rituximab. Therefore, a timely diagnosis can help slow down or prevent symptomatic manifestations, as seen in the case. Clinicians should be aware of this clinical presentation.