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Background Immunoglobulin G4 (IgG4)-related disease is an entity that can involve the thyroid gland. The spectrum of IgG4-related thyroid disease (IgG4-RTD) includes Hashimoto thyroiditis (HT) and its fibrotic variant, Riedel thyroiditis, as well as Graves’ disease. The early diagnosis of IgG4-RTD is important because it is a medically treatable disease, and a delay in the diagnosis might result in unnecessary surgery. We present a case series of IgG4-RTD with a review of the literature. Methods We retrospectively reviewed the clinical presentation and the radiological and pathological findings of patients diagnosed with IgG4-RTD between 2017 and 2021 at a tertiary medical center in Korea. We also conducted a literature review of IgG4-RTD. Results Five patients were diagnosed with IgG4-RTD during the study period. The patients’ age ranged from 31 to 76 years, and three patients were men. Most patients visited the clinic for a neck mass, and hypoechogenic nodular lesions were observed on neck ultrasonography. Three patients had IgG4 HT, and two patients had IgG4 Riedel thyroiditis. All patients developed hypothyroidism that necessitated L-thyroxine replacement. The diagnosis of IgG4-RTD was confirmed after a pathological examination of the surgical specimen in the first two cases. However, the early diagnosis was possible after a core needle biopsy in three clinically suspected patients. Conclusion The diagnosis of IgG4-RTD requires clinical suspicion combined with serology and histological analyses using IgG4 immunostaining. The early diagnosis of IgG4-RTD is difficult; thus, biopsy with IgG4 immunostaining and serum IgG4 measurements will help diagnose patients suspected of having IgG4-RTD.

Background : Retroperitoneal fibrosis (RPF) is a rare disease characterized by fibroinflammatory tissue in the periaortic or periiliac retroperitoneum, where it frequently encases ureters. There is emerging evidence that a subset of this disease is part of a spectrum of multisystemic autoimmune diseases collectively referred to as “immunoglobulin G4 (IgG4)-related disease”. Methods : We retrospectively analyzed 27 idiopathic RPF patients and identified a subset as IgG4-related RPF, which we categorized according to recently published comprehensive diagnostic criteria. We compared clinical and laboratory characteristics and response to treatment between the two groups. Results : Of 27 total patients, 16 (59.3%) were diagnosed as having IgG4-related RPF, and these were predominantly male. They were also significantly older and more likely to have other organ involvement, hydronephrosis, and postrenal acute kidney injury (AKI) compared to those with idiopathic RPF. However, there was no difference in response rate to systemic steroid treatment. Conclusion : IgG4-related RPF accounts for a substantial portion of RPF cases previously identified as “idiopathic RPF” in Korea. Clinical and laboratory characteristics of IgG4-related RPF are similar to those of idiopathic RPF except for a striking male predominance, older age, and higher incidence of postrenal AKI in IgG4-related RPF. More comprehensive, prospective studies are needed to clearly distinguish IgG4-related RPF from idiopathic RPF based on clinical manifestation and to further assess treatment response and long-term prognosis.

Background Immunoglobulin G4 (IgG4) related disease is an immune-mediated fibroinflammatory condition that can affect multiple organs. There are only few reports of pachymeningeal involvement by IgG4 related disease in Korea. Case Report A 50-year-old woman was admitted due to generalized seizure and headache. Brain magnetic resonance imaging (MRI) showed nodular dural thickening and enhancement in the right frontal areas. A meningeal biopsy was performed. On pathology, chronic inflammation, fibrosis and plasma cell infiltration were revealed. Immunoglobulin G4 immunohistochemistry showed prominent IgG4+ plasma cell infiltrate. Serum IgG level was normal but IgG4 subclass level was significantly elevated. She was treated with intravenous dexamethasone followed by oral prednisolone. After 1 year of treatment, brain MRI showed marked decrease of dural thickening and enhancement. Conclusion We report a case of IgG4 related pachymeningitis improved with corticosteroid. IgG4 related disease should be included in the differential diagnosis in patients with hypertrophic pachymeningitis.

Isolated gastric IgG4-related disease (IgG4-RD) is a very rare tumefactive inflammatory condition, with only a few cases reported to date. A 48-year-old woman was incidentally found to have a subepithelial tumor in the stomach. Given a presumptive diagnosis of gastrointestinal stromal tumor or neuroendocrine tumor, she underwent wedge resection. The lesion was vaguely nodular and mainly involved the submucosa and proper muscle layer. Microscopically, all classical features of type I autoimmune pancreatitis including lymphoplasmacytic infiltration, storiform fibrosis, obliterative phlebitis, and numerous IgG4-positive plasma cells were seen. She had no evidence of IgG4-RD in other organs. Although very rare, IgG4-RD should be considered one of the differential diagnoses in the setting of gastric wall thickening or subepithelial mass-like lesion. Deep biopsy with awareness of this entity might avoid unnecessary surgical intervention.

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is rare disease which is steroid-responsive and often associated with IgG4 related systemic disease such as autoimmune pancreatitis. It is characterized by increased serum IgG4 and IgG4- positive lymphoplasmacytic infiltration in bile ducts. It is often difficult to distinguish IgG4-SC to hilar cholangiocarcinoma if it manifests as an isolated bile duct. We report a case of 79-year-old woman with IgG4-SC which was difficult to distinguish hilar cholangiocarcinoma due to similar clinical and radiologic findings, showing good therapeutic effect after a 2-week steroid trial. [ABSTRACT FROM AUTHOR]

Immunoglobulin G4-related disease (IgG4-RD) is characterized by extensive IgG4- positive plasma cells infiltration resulting in inflammation and fibrosis of the affected organs. Patient with IgG4-RD shows an excellent response to glucocorticoid therapy especially when given at early onset stages. IgG4-related sclerosing cholangitis (IgG4- SC) is considered biliary manifestation of IgG4-RD. The natural history and longterm prognosis of IgG4-SC is not well defined and most of the previous case series have reported short duration of follow-up. We present the case of development of decompensated liver cirrhosis from IgG4-related sclerosing cholangitis with a 6-year natural clinical course. [ABSTRACT FROM AUTHOR]

Immunoglobulin G4 (IgG4)-related sclerosing disease (RSD) is a chronic inflammatory disorder characterized by elevated serum IgG4 levels as well as an abundant infiltration of IgG4-positive plasmacytes. Involvement of the paranasal sinus is very rare, so it is difficult to make an accurate diagnosis. Hence, various differential diagnoses, which typically include elevated serum IgG4 levels and the infiltration of IgG4-postive cells into tissues, need to be excluded, especially for malignant diseases and mimicking disorders. Systemic corticosteroids are generally effective at inducing IgG4-RSD remission. Recently, a 43-yearold woman presented with a mass originating from the ethmoid sinus, suggesting malignancy. The patient underwent biopsy of the lesion. The pathologic specimen revealed the magnitude of IgG4-positive plasma cell infiltration, which was consistent with IgG4-RSD. In addition, serum IgG4 levels were markedly increased. After glucocorticoid treatment, the serum IgG4 levels decreased and the symptoms improved. We present a rare case of IgG4-RSD with isolated involvement of the paranasal sinuses. [ABSTRACT FROM AUTHOR]

Immunoglobulin (Ig) G4-related sclerosing disease is a recently described systemic fibro-inflammatory disease associated with an elevated circulating level of IgG4 and extensive IgG4-positive lymphoplasmacytic infiltration, resulting in sclerosing inflammation involving various body organs. We experienced one case where surgery confirmed IgG4-related sclerosing disease as a solitary lung mass mimicking lung cancer. We report radiologic findings including chest computed tomography and positron emission tomography computed tomography, with clinical manifestations of IgG4-related sclerosing disease. [ABSTRACT FROM AUTHOR]