Diagnostic Difficulties in IGG4-Related Disease

Introduction Infiltration, accumulation of IgG4+ plasma cells, and fibrosis are important constituents of a rare IgG4-related disease (IgG4RD) with prevalence of 0,78 to 1,39 per 100,000 population.[1,2] Capable of damaging any organ, the pancreas and salivary glands (SGs) are indicated among the most frequent targets. [3] Case Presentation A 41-year-old female was hospitalized due to pruritus, hypertrophy of the SGs, weight loss, and pain under the left rib cage, present since adolescence. The patient was followed for chronic idiopathic pancreatitis. Comorbidities include osteoporosis, amenorrhea, autoimmune thyroiditis, type II diabetes, CKD stage II, and outpatient psychiatric treatment, with suspected but not confirmed bulimia. Objectively, a painful abdomen in both superior quadrants, hypertrophic parotid glands bilaterally with mandible restriction, and a BMI of 11,97 kg/cm2 were documented. Laboratory work unveiled elevated α-amylase with pancreatic amylase at normal levels. A decade of monitoring the symptoms led to the suspicion of IgG4RD after the elevation of IgG4 (2 g/l) was noticed retrospectively. Diagnostic tests, including CT, disclosed the pancreas as atrophic, intraparenchymal, containing intraductal concrements. Parotid gland US confirmed their heterogeneous structure and enlargement. Consillium confirmed the IgG4RD diagnosis with its manifestations: chronic autoimmune pancreatitis, autoimmune sialadenitis, and early phase of IgG4RD-associated sclerosing cholangitis. Before glucocorticoid (GC) therapy, osteoporosis management was corrected and a biopsy from SGs was taken. Aside from the symptomatic and malnutrition treatment, prednisolone therapy was started with the continuation planned outpatiently. For maintenance, mycophenolate mofetil (MM) was prescribed and noticeably improved the condition. Discussion Distorted innate and adaptive immunity results in excess synthesis of IgG4, which is a diagnostic finding in the blood. IgG4+ plasma cell infiltration and fibrosis can be seen histologically. [1] The first-line therapy for IgG4RD is GCs. As a broader strategy azathioprine, MM, methotrexate can be prescribed. [3,4] Conclusions This case report highlights the importance of IgG4RD suspicion while detecting multiorgan violation along with chronic pancreatitis.