IgG4‐related retroperitoneal fibrosis: a newly characterized disease

Retroperitoneal fibrosis (RPF) is a rare disease characterized by chronic, nonspecific inflammatory and sclerotic or fibrotic tissue in the periaortic or periiliac retroperitoneum that encases adjacent structures. There will be a series of clinical manifestations once the proliferated fibrous tissues encase the abdominal aorta, iliac arteries and urinary duct. RPF is generally divided into two types: idiopathic retroperitoneal fibrosis (IRPF) without identified pathogenesis, making up about two‐thirds of cases, and secondary retroperitoneal fibrosis. Recent studies on Immunoglobulin G4‐related disease (IgG4‐RD) reveal that abundant infiltration of IgG4 positive plasma cells is found in biopsies on the mass of RPF of some IRPF patients, which is identified as one spectrum of IgG4‐RD and is named IgG4‐related RPF. IgG4‐related RPF is often misdiagnosed as retroperitoneal visceral malignancy and is treated with surgery. In addition, because of its good response to glucocorticoid, early detection and treatment is important. We review the definition, epidemiology, clinical features, diagnostic criteria, treatment and prognosis of IgG4‐related RPF in this article to raise awareness of this newly characterized disease.     

Medical mirroring: granulomatosis with polyangiitis (formerly Wegener's) mimicking immunoglobulin‐G4 related disease

Granulomatosis with polyangiitis (GPA; formerly Wegener's) can present with clinical and histopathological features similar to those of immunoglobulin‐G4 related disease (IgG4‐RD), a recently described fibro‐inflammatory condition. The ability of these two distinct entities to mimic each other closely creates significant pitfalls in diagnosis. We present a unique case in which GPA presented as a peri‐aortic fibrotic mass in the retroperitoneum. The patient's other clinical features also overlapped with classic IgG4‐RD disease manifestations, but the histopathology in two organs and the serological data confirmed the diagnosis of GPA. Rigorous histopathological review remains the gold standard for the diagnosis of GPA and the distinction of this entity from IgG4‐RD and other mimickers.     

IgG4‐related disease with hypergammaglobulinemic hyperviscosity and retinopathy

Immunoglobulin G4‐related disease (IgG4‐RD) is a recently described entity with protean manifestations. We describe a novel case of IgG4‐RD with hypergammaglobulinemic hyperviscosity responsive to fludarabine and rituximab. A 33‐year‐old Asian man developed bilateral lacrimal gland and submandibular salivary gland swelling with cervical lymphadenopathy. Biopsies of the affected tissues revealed reactive follicular hyperplasia. Seven years later, he presented with bilateral retinal hemorrhages due to hyperviscosity syndrome from profound polyclonal increase in IgG, including marked IgG4 elevation. Despite plasmapheresis, overproduction of IgG continued and he was refractory to systemic steroids, azathioprine, interferon alpha, and cyclophosphamide. IgG4‐RD was suspected following a myocardial infarction and detection of aneurysmal coronary arteries indicating large vessel vasculitis. Review of the cervical lymph node and lacrimal gland biopsies with immunohistochemical staining for IgG4‐positive plasma cells confirmed IgG4‐RD. B‐cell depletion with rituximab produced a partial response, but clinical symptoms and elevated protein levels persisted. Fludarabine was added to rituximab to suppress T‐cell activity, and this resulted in an excellent clinical and biochemical response. Combination therapy with fludarabine and rituximab in IgG4‐RD has not previously been reported and can be considered in patients with severe refractory disease.     

Evaluation of submandibular versus labial salivary gland fibrosis in IgG4-related disease

Abstract

The newly comprehensive diagnostic criteria in 2011 emphasize the importance of IgG4-positive plasmacyte infiltration along with storiform or swirling fibrosis and obliterative phlebitis in diagnosing IgG4-related disease(RD). Although labial salivary gland (LSG) biopsy is a minimally invasive and convenient procedure for obtaining tissues, LSG fibrosis is thought to be inconspicuous or absent in IgG4-RD cases. In this study we evaluated 15 patients with IgG4-RD, in whom both submandibular gland (SMG) and LSG biopsies were performed at the same time. Histological evaluation revealed fibrosis in all the SMG specimens but in only one LSG specimen (6.7%). The diagnosis of IgG4-RD is primarily based on its morphological appearance on biopsy. The results of this study demonstrated that although more invasive than LSG biopsy, SMG biopsy is recommended for accurate diagnosis of IgG4-related MD and to exclude malignant diseases.     

Immunoglobulin G4‐related sclerosing cholangitis

Immunoglobulin (Ig)G4‐related sclerosing cholangitis (IgG4‐SC) is a biliary tract manifestation of IgG4‐related diseases (IgG4‐RD); a subgroup of SC defined as a condition with progressive stenosis and destruction of the bile ducts due to diffuse inflammation and fibrosis. IgG4‐SC is clinically characterized by the (a) chronic elevation of cholestatic enzyme levels, (b) significant elevation of serum IgG4 levels, (c) diffuse or segmental narrowing of intra and/or extra hepatic bile ducts with thickening of the bile duct wall in imaging studies, (d) marked lymphoplasmacytic and IgG4‐positive plasma cell infiltration and fibrosis in histology, (e) presence of IgG4‐RD in other organs, mainly involving autoimmune pancreatitis, and (f) excellent response to corticosteroids. The diagnosis of IgG4‐SC is based on a combination of these findings. Although the IgG4‐SC diagnosis is different from that of primary sclerosing cholangitis (PSC) or biliary and pancreatic malignancies, it is extremely important to diagnose or suspect IgG4‐SC appropriately; as the incorrect diagnosis of PSC or malignant diseases may lead to the progression of fibrosis in patients due to untreated chronic cholestasis, or to unnecessary major surgical resections. Although its etiology remains unclear, recent studies of IgG4‐SC have attempted to clarify the roles of the IgG4 molecule and novel autoantibodies detected in patients with IgG4‐SC.     

IgG4相关性疾病

IgG4相关性疾病是一种与IgG4淋巴细胞密切相关的慢性、系统性疾病,该类疾病以血清IgG4水平升高以及IgG4阳性细胞浸润多种器官和组织为特征,常见受累器官包括泪腺、胰腺和腹膜后间隙等,累及的器官或组织由于慢性炎症及纤维化进程可导致弥漫性肿大。该类疾病对皮质激素治疗反应良好。     

Possible participation of IgG4 in the activation of complement in IgG4-related disease with hypocomplementemia

Objective: To investigate which IgG subclasses contribute to the activation of the complement pathway in IgG4-related disease (IgG4RD) patients with hypocomplementemia.

Methods: Sera of IgG4RD patients were analyzed for the binding ability of IgG subclasses to complement component 1q (C1q). Polyethylene glycol (PEG) precipitates containing immune complexes (ICs) in sera of IgG4RD patients were analyzed for IgG subclass composition by Western blotting. PEG precipitates containing ICs (PEG-ICs) in sera of patients were also analyzed for their ability to consume complement in normal human serum (NHS) using a total complement hemolytic (CH50) assay and a commercial kit to measure the complement capacity of all three individual complement pathways.

Results: The C1q binding assay revealed high serum levels of C1q-binding IgG4 in IgG4RD patients with hypocomplementemia. ICs in PEG precipitates were formed with IgG4 in IgG4RD patients, regardless of the presence or absence of hypocomplementemia. We observed a marked reduction of CH50 and reduced complement activity in the classical complement pathway as well as the mannan-binding lectin complement pathway in NHS incubated with PEG-IC isolated from IgG4RD patients with hypocomplementemia.

Conclusion: Our results suggest that IgG4 may participate in the activation of complement in IgG4RD patients with hypocomplementemia.     

A novel clinical entity, IgG4-related disease (IgG4RD): general concept and details

IgG4-related disease (IgG4RD) is a novel clinical disease entity characterized by elevated serum IgG4 concentration and tumefaction or tissue infiltration by IgG4-positive plasma cells. IgG4RD may be present in a certain proportion of patients with a wide variety of diseases, including Mikulicz's disease, autoimmune pancreatitis, hypophysitis, Riedel thyroiditis, interstitial pneumonitis, interstitial nephritis, prostatitis, lymphadenopathy, retroperitoneal fibrosis, inflammatory aortic aneurysm, and inflammatory pseudotumor. Although IgG4RD forms a distinct, clinically independent disease category and is attracting strong attention as a new clinical entity, many questions and problems still remain to be elucidated, including its pathogenesis, the establishment of diagnostic criteria, and the role of IgG4. Here we describe the concept of IgG4RD and up-to-date information on this emerging disease entity.     

Dacrioadenitis por enfermedad relacionada con IgG4 en una adolescente afrodescendiente de Colombia

IgG4-related disease (IgG4-RD) is a recently recognized clinical condition with multiple aspects not yet elucidated. It is characterized by a fibrous inflammatory process that involves multiple organs and clinical, serological and histopathological findings, which represent a major challenge for the clinician. Classically described as an expansive tumor lesion with storiform fibrosis, lymphoplasmacytic infiltration (IgG4-positive) and elevated serum IgG4. Clinical features are variable, and pancreatic as well as extrapancreatic involvement has been reported, more frequently in Asian men over 50 years and rarely described in black people. We report the case of an Afro-Colombian teenage woman, who had a unilateral ocular protrusion of unknown cause, with histopathologic findings that revealed infiltration of lymphocyte and plasma cells into the lacrimal gland. It was positive for IgG4, ruling out other conditions, and confirming IgG4-related dacryoadenitis.     

IgG4-related retroperitoneal fibrosis: the first reported case in a Chinese population

Immunoglobulin G4 (IgG4)-related sclerosing disease is a newly recognized clinicopathological entity characterized by lymphoplasmacytic infiltration and varying degrees of fibrosis in various organs, with abundant IgG4-positive plasma cells in tissues. Patients usually exhibit multisystem involvement and often respond well to steroid and immunosuppressive therapy. However, this disease has been rarely reported in a Chinese population. We herein report a case of IgG4-related sclerosing disease solely presenting with retroperitoneal fibrosis that was effectively treated with systemic steroid therapy. To the best of our knowledge, this is the first reported case of IgG4-related retroperitoneal fibrosis in a Chinese population.     

Review of primary sclerosing cholangitis with increased IgG4 levels

Primary sclerosing cholangitis(PSC) is a chronic progressive liver disease. Subtypes of PSC have been described, most recently PSC with elevated serum and/or tissue IgG4 subclass. We aim to summarise the clinical phenotype,disease associations, differential diagnosis, response to therapy and pathogenic mechanisms underlying PSC-high IgG4 subtype. We reviewed Pub Med,MEDLINE and Embase with the search terms "primary sclerosing cholangitis","IgG4", and "IgG4-related sclerosing cholangitis(IgG4-SC)". Elevated serum IgG4 are found in up-to one-quarter, and abundant IgG4-plasma cell infiltrates in the liver and bile ducts are found in up-to one-fifth of PSC patients. This group have a distinct clinical phenotype, with some studies reporting a more aggressive course of liver and associated inflammatory bowel disease, compared to PSCnormal IgG4 and the disease mimic IgG4-SC. Distinguishing PSC-high IgG4 from IgG4-SC remains challenging, requiring careful assessment of clinical features,organ involvement and tissue morphology. Calculation of serum IgG4:IgG1 ratios and use of a novel IgG4:IgG RNA ratio have been reported to have excellent specificity to distinguish IgG4-SC and PSC-high IgG4 but require validation in larger cohorts. A role for corticosteroid therapy in PSC-high IgG4 remains unanswered, with concerns of increased toxicity and lack of outcome data. The immunological drivers underlying prominent IgG4 antibodies in PSC are incompletely defined. An association with PSC-high IgG4 and HLA class-II haplotypes(B*07, DRB1*15), T-helper2 and T-regulatory cytokines(IL4, IL10,IL13) and chemokines(CCL1, CCR8) have been described. PSC-high IgG4 have a distinct clinical phenotype and need careful discrimination from IgG4-SC,although response to immunosuppressive treatments and long-term outcome remains unresolved. The presence of IgG4 likely represents chronic activation to persistent antigenic exposure in genetically predisposed individuals.     

Acute Tubulointerstitial Nephritis in Rosai-Dorfman Disease Mimicking IgG4-related Disease

Rosai-Dorfman-Destombes disease (RDD) is a non-Langerhans cell histiocytosis characterized by the accumulation of histiocytes inside the lymph nodes or extranodally. The association between RDD and IgG4-related disease (IgG4-RD) is discussed. We herein report a case of RDD manifesting as acute tubulointerstitial nephritis mimicking IgG4-RD. The first renal biopsy showed severe tubulointerstitial nephritis with infiltration of S100-positive histiocytes and IgG4-positive plasma cells; storiform fibrosis and obliterative phlebitis were not confirmed. After prednisolone therapy, IgG4-positive cells and S100-positive histiocytes were decreased, but the IgG4/IgG ratio increased despite clinical improvement. These findings indicated extranodal RDD in the kidney presenting as tubulointerstitial nephritis.     

IgG4-related sclerosing disease

Based on histological and immunohistochemical exami- nation of various organs of patients with autoimmune pancreatitis （AIP）, a novel clinicopathological entity of IgG4-related sclerosing disease has been proposed. This is a systemic disease that is characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs. Clinical manifestations are apparent in the pancreas, bile duct, gallbladder, salivary gland, retroperitoneum, kidney, lung, and prosrate, in which tissue fibrosis with obliterative phlebitis is pathologically induced. AlP is not simply pancreatitis but, in fact, is a pancreatic disease indicative of IgG4- related sclerosing diseases. This disease includes AlP, sclerosing cholangitis, cholecystitis, sialadenitis, retro-peritoneal fibrosis, tubulointerstitial nephritis, interstitial pneumonia, prostatitis, inflammatory pseudotumor and lymphadenopathy, all IgG4-related. Most IgG4-related sclerosing diseases have been found to be associated with AlP, but also those without pancreatic involvement have been reported. In some cases, only one or two organs are clinically involved, while in others, three or four organs are affected. The disease occurs predominantly in older men and responds well to steroid therapy. Serum IgG4 levels and immunos-taining with anti-IgG4 antibody are useful in making the diagnosis. Since malignant tumors are frequently suspected on initial presentation, IgG4-related sclerosing disease should be considered in the differential diagnosis to avoid unnecessary surgery.     

Prevalence and distribution of extrapancreatic lesions complicating autoimmune pancreatitis

Background Autoimmune pancreatitis is a unique form of chronic pancreatitis characterized by high serum IgG4 concentrations and abundant IgG4-bearing plasma cell infiltration in the pancreatic lesion, and it has been reported to be associated with a variety of extrapancreatic lesions, leading us to postulate the concept of a systemic inflammatory disease. To confirm this, we clarified the exact distribution of these extrapancreatic lesions and provide a panoramic view of them. Methods The frequency, distribution, clinical characteristics, and pathology of five extrapancreatic lesions were determined in 64 patients with autoimmune pancreatitis by examining clinical and laboratory findings. Results The most frequent extrapancreatic lesion was hilar lymphadenopathy (80.4%), followed by extrapancreatic bile duct lesions (73.9%), lachrymal and salivary gland lesions (39.1%), hypothyroidism (22.2%), and retroperitoneal fibrosis (12.5%). No patients had all five types of lesions. Patients with hilar lymphadenopathy or lachrymal and salivary gland lesions were found to have significantly higher IgG4 levels than those without (P = 0.0042 and 0.0227, respectively). Patients with three lesions were found to have significantly higher IgG4 levels than those with no lesion, suggesting that patients with multiple extrapancreatic lesions have active disease. Similar to pancreatic lesions, extrapancreatic lesions have a characteristic histological finding of abundant IgG4-bearing plasma cell infiltration, and they respond favorably to corticosteroid therapy. Conclusions Autoimmune pancreatitis was recognized as a systemic inflammatory disease. Furthermore, recognition of these characteristic findings will aid in the correct diagnosis of this disease.     

Autoimmune Pancreatitis: Updated Concepts of a Challenging Diagnosis

Autoimmune pancreatitis is a benign process characterized by inflammation and fibrosis. It is now known that cases of “autoimmune pancreatitis” actually consist of two distinct pathologic entities. Type 1 autoimmune pancreatitis is a manifestation of a systemic process, immunoglobulin G subclass 4 (IgG4)-related disease. IgG4-related disease can affect virtually every organ system in the body. Type 1 affects older patients and is characterized by an elevated serum IgG4 level and sites of extrapancreatic disease. Type 2 autoimmune pancreatitis is a disease process confined to the pancreas. It affects younger patients and is associated with inflammatory bowel disease. Type 2 is not associated with elevated IgG4 levels or extrapancreatic disease. Both subtypes can mimic malignancy, particularly pancreatic cancer. Awareness of the clinical and imaging features of the subtypes of autoimmune pancreatitis is important to avoid an incorrect diagnosis of malignancy.     

Deconstructing IgG4-related disease involvement of midline structures: Comparison to common mimickers

Objective: A series of destructive and tumefactive lesions of the midline structures have been recently added to the spectrum of IgG4-related disease (IgG4-RD). We examined the clinical, serological, endoscopic, radiological, and histological features that might be of utility in distinguishing IgG4-RD from other forms of inflammatory conditions with the potential to involve the sinonasal area and the oral cavity.

Methods: We studied 11 consecutive patients with erosive and/or tumefactive lesions of the midline structures referred to our tertiary care center. All patients underwent serum IgG4 measurement, flow cytometry for circulating plasmablast counts, nasal endoscopy, radiological studies, and histological evaluation of tissue specimens. The histological studies included immunostaining studies to assess the number of IgG4?+?plasma cells/HPF for calculation of the IgG4+/IgG?+?plasma cell ratio.

Results: Five patients with granulomatosis with polyangiitis (GPA), three with cocaine-induced midline destructive lesions (CIMDL), and three with IgG4-RD were studied. We found no clinical, endoscopic, or radiological findings specific for IgG4-RD. Increased serum IgG4 and plasmablasts levels were not specific for IgG4-RD. Rather, all 11 patients had elevated blood plasmablast concentrations, and several patients with GPA and CIMDL had elevated serum IgG4 levels. Storiform fibrosis and an IgG4+/IgG?+?plasma cell ratio >20% on histological examination, however, were observed only in patients with IgG4-RD.

Conclusions: Histological examination of bioptic samples from the sinonasal area and oral cavity represents the mainstay for the diagnosis of IgG4-RD involvement of the midline structures.     

Immunoglobulin G4 (IgG4)-related autoimmune hepatitis and IgG4-hepatopathy: A histopathological and clinical perspective

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a chronic inflammatory disease that simultaneously or consecutively involves multiple organs of the body. It is characterized by elevated serum IgG4 levels and massive infiltration of IgG4⁺ plasma cells in the damaged tissues. IgG4-related autoimmune hepatitis (IgG4-AIH) and IgG4-hepatopathy are relatively new entities that have been proposed as a phenotype of IgG4-RD in the liver. Immunoglobulin G4-AIH is defined as a disorder with serological, histopathological, and clinical features of both IgG4-RD and AIH, simultaneously satisfying the diagnostic criteria of both classical AIH and IgG4-RD. Although there are several case reports and studies of IgG4-AIH among the published works, no consensus regarding the histopathological characteristics of IgG4-AIH has been established, and its clinical implications remain obscure. Immunoglobulin G4-hepatopathy is defined as a comorbidity of IgG4-RD in the liver, and patients not meeting the diagnostic criteria of classical AIH could be diagnosed with IgG4-hepatopathy. Numerous issues regarding these diseases, especially their epidemiology, histopathological and clinical characteristics, and treatment response to corticosteroids, remain unsolved, and need to be determined to establish the disease concepts of IgG4-AIH and IgG4-hepathopathy.     

Thoracic manifestations of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a recently described rare systemic fibroinflammatory disease with an estimated incidence of less than 1 in 100,000 persons per year. The disease can affect virtually any organ and is characterized by unifying histopathological findings. Recently, four subgroups of patients have been characterized: hepatobiliary, head and neck, Mikulicz syndrome and retroperitoneal fibrosis, who illustrate the mainly abdominal and ENT tropism of the disease. Yet, thoracic involvement is not uncommon. It can be detected in up to 30% of patients with systemic IgG4-RD and is the exclusive manifestation of the disease in about 10% of cases. Clinical symptoms are nonspecific and may include dyspnoea, cough or chest pain. Chest CT findings are heterogeneous and primarily include peribronchovascular thickening, nodules, ground-glass opacities and lymphadenopathy. There is no specific diagnostic test for IgG4-RD thoracic involvement, which may mimic malignancy or vasculitis. Therefore, a cautious approach is needed to make an accurate diagnosis: a search for extra-thoracic manifestations, elevated serum IgG4 levels, circulating levels of plasmablasts and pathologic evidence of disease is warranted. Although very suggestive, neither the presence of a polyclonal IgG4 lymphoplasmacytic infiltrate, storiform fibrosis or obliterative phlebitis are sufficient to confirm the histological diagnosis. Steroids are recommended as first-line therapy. Rituximab or disease-modifying antirheumatic drugs may be used in relapsed or rare cases of steroid-refractory disease. In this review, we summarize current knowledge regarding the pathophysiology, epidemiology, diagnostic modalities (clinical–biological–imaging–histopathology) and treatment of IgG4-RD thoracic involvement.     

Investigations of IgG4-related disease involving the skin

Objectives

IgG4-related skin disease is not widely recognized. This prompted us to investigate the clinical and pathological features of five patients we encountered with IgG4-related disease (IgG4-RD) affecting the skin.

Methods

We investigated the clinical and pathological features of these five patients, including the distribution, onset, and morphology of eruptions, their pathological and immunohistochemical characteristics, and the occurrence of disease in other organs.

Results

The skin lesions were typically erythematous nodules and papules and brown papules like prurigo nodularis, which developed on the face or in the head and neck areas in four patients. Skin lesions were the first clinical manifestation in three patients. All five patients had sialadenitis and/or dacryoadenitis. The mean serum IgG4 concentration was 665.6 ± 410.0 mg/dl. Infiltrations of IgG4-positive plasma cells were observed in both the dermis and subcutaneous tissue. Germinal center formations were seen in three patients. Mild to moderate fibrosis was observed in all patients, and focal obliterative phlebitis in one. The average count of IgG4-positive cells was 67.3/high-power field (23.0–128.6). Wide variation in the numbers of infiltrating IgG4-positive cells was noted.

Conclusion

IgG4-RD appears to have a distinctive clinicopathological presentation in the skin, differentiating it from other cutaneous disorders.