General principles of IgG4-related disease

Clinical manifestations of chronic pancreatitis in English cocker spaniels

BACKGROUND

Chronic pancreatitis (CP) is common in English cocker spaniels (ECS). It is histologically similar to IgG4-related disease (IgG4-RD) in humans and is characterized by duct destruction, interlobular fibrosis, and dense periductular and perivenous lymphocytic aggregates. However, the clinical manifestations of CP in ECS have not been previously described.

OBJECTIVES

Characterize the clinical manifestations of CP in a group of ECS, including similarities and differences to IgG4-RD in humans.

ANIMALS

One-hundred four ECS with CP and 44 client owned control ECS without CP (both healthy and diseased controls).

METHODS

Affected dogs were divided into 2 groups according to the methods used to diagnose CP. Case records were searched for signalment, clinical, and clinicopathological findings, and evidence of keratoconjunctivitis sicca (KCS), proteinuria, other immune-mediated diseases, and anal sacculitis.

RESULTS

Involvement of other organs was common. Affected ECS presented with a high frequency of KCS (n = 49), proteinuria (n = 47), anal gland disease (n = 36), atopy (n = 21), and other immune-mediated diseases (n = 16). Those with parti-color hair coats, particularly blue roan, had a strong association with CP, suggesting a link between coat color and autoimmune conditions in this breed.

CONCLUSIONS AND CLINICAL IMPORTANCE

English cocker spaniels with CP show clinical similarities to humans with IgG4-RD and common involvement of other organs. Clinicians should evaluate affected Cocker Spaniels for proteinuria, keratoconjunctivitis sicca, and other potential immune-mediated diseases.

Challenges and pitfalls in the diagnosis of IgG4-related disease

IgG4-related disease (IgG4-RD) is a relatively novel fibroinflammatory condition characterized typically by dense lymphoplasmacytic inflammation, storiform fibrosis and obliterative venulitis, together with prominent IgG4+ plasma cells and an IgG4+/IgG+ plasma cell ratio of >40 %. The diagnosis is usually made on a combination of clinical and serological features together with characteristic radiological and histological appearances. The condition may be limited to a single tissue/organ (e.g., autoimmune pancreatitis) or may be multicentric in nature - four clinical 'patterns' of disease distribution have recently been described. The diagnosis of IgG4-RD can be challenging, particularly when the clinical presentation is unusual and/or when the histological features are not typical. A diagnosis of IgG4-RD may still be achieved in these situations, after careful clinicopathological discussion e.g., at a specialist multidisciplinary team meeting. However, a wide range of other conditions (neoplastic and non-neoplastic) can mimic IgG4-RD, clinically and/or on histological examination. The relationship between IgG4-RD and non-IgG4-RD associated conditions in some clinical situations is particularly complex. This review describes the role of histological examination in the diagnosis of IgG4-RD, discusses some of the practical difficulties that may be encountered and provides an insight into the range of non-IgG4-RD associated conditions that can mimic IgG4-RD on clinical and/or histological grounds. The requirement for interpretation of histological features in the context of the global clinical picture of the patient is highlighted and emphasized.

IgG4 related disease and aortitis: an up-to-date review

Aortic involvement in immunoglobulin G4-related disease (IgG4-RD) is extremely rare and is often overlooked during the aortitis work-up. IgG4-related aortitis differs from non-IgG4-related aortitis in its histopathological features, site of involvement, laboratory markers, and treatment options. The histopathological examination of the vessel walls characteristically reveals adventitial thickening with intimal sparing, typically affecting the infrarenal abdominal aorta. In addition, inadequate knowledge about the disease often leads to delayed or missed diagnosis and undermanagement of a potentially treatable condition. Hence, in this paper, we review the unique clinical manifestations, laboratory markers, diagnostic features, current treatment strategies, and novel experimental therapeutic options in the management of IgG4-related aortitis.

IgG4-related disease: an analysis of the clinicopathological spectrum: UK centre experience

AIM

To retrospectively evaluate the characteristic clinicopathological spectrum in patients with suspicion of IgG4-related disease (IgG4RD).

METHODS

Winpath histology database from January 2011 to April 2018 identified all suspected IgG4RD cases wherein IgG4 immunohistochemistry was performed. The histology slides were reviewed to categorise cases into Boston criteria groups-highly suggestive of IgG4RD, probable IgG4RD and insufficient evidence. Information regarding clinical data, treatment received, follow-up and serum IgG4 levels was obtained from medical records and AllScripts Patient Administration System (APAS) clinical database.

RESULTS

The study included 204 patients and the most common sites of biopsy/resection were pancreas and duodenum. The most common clinical presentation was fibroinflammatory lesion or mass/lump. On histology, 54/204 (26.47%) cases showed typical storiform fibrosis, 65/204 (32.64%) had >10 IgG4+ plasma cells per high power field and only one case showed thrombophlebitis (0.49%). There were 14/204 (6.78%) cases categorised as highly suggestive of IgG4RD; 8 of these showed high serum IgG4 levels and were managed clinically as true IgG4RD.

CONCLUSION

Histological diagnosis of IgG4RD remains challenging, as not all characteristic features are always present especially in small biopsies. Due to the novelty of its experience, fear of over diagnosis in the context of malignancy and features overlapping with diseases of similar clinical scenario, diagnosis of IgG4RD has become more puzzling. Further multicentre clinical trials/studies are advisable.

Immunological characteristics of IgG4-related Kuttner tumors

Immunoglobulin G4-related disease (IgG4-RD) has recently been well recognized and Kuttner tumor is known to be a chronic sclerosing sialadenitis, representing the focal manifestation of IgG4-RD, in the submandibular gland (SMG). This study is to evaluate the immunologic features of IgG4-related Kuttner tumor in the SMG. We retrospectively chose 13 patients who were confirmed as having Kuttner tumor by surgical biopsy between May 2012 and January 2019. The fine-needle aspiration cytology, serum antibody levels (anti-Ro antibodies, anti-La antibodies), IgG serum levels (total IgG and IgG4), and immunohistochemical findings for IgG and IgG4-positive plasma cells were reviewed. The cytologic results found that 7 of the 9 cases were reported as chronic sialoadenitis, and the other 3 as benign lymphoproliferative lesion. The serum levels of autoantibodies, Sjögren-syndrome-related antigen A/Ro-Ab and Sjögren-syndrome-related antigen A/Ro-La, showed all normal values of serum level. The serum level of IgG was increased in only 4 among the cases. However, the IgG4 levels were significantly increased in 11 among the cases. In all the patients who received resection of SMG, immunohistochemical findings showed all positive for IgG4-RD, with elevated numbers of IgG and IgG4-positive plasma cells. The evaluation of IgG4 serum level should be very informative for the diagnosis of this tumor before surgery. Fine-needle aspiration cytology with ultrasound guidance are not conclusive in this study. The immunological study including IgG4 serum level should be required for proper diagnosis and treatment, with clinical features of the Kuttner tumor. The level of evidence was IV.

Chronic Inflammatory Disease in the Pancreas, Kidney and Salivary Glands of English Cocker Spaniels and Dogs of Other Breeds Shows Similar Histological Features to Human IgG4-related Disease

Chronic pancreatitis (CP) is a common disease in the English cocker spaniel (ECS) and is characterized histologically by duct destruction, interlobular fibrosis and dense periductular and perivenous lymphocytic aggregates. These features are also found in human autoimmune pancreatitis type 1, part of a glucocorticoid-responsive, multiorgan syndrome, newly recognized as IgG4-related disease (IgG4-RD). Human IgG4-RD affects one or several organs, often showing a predominance of IgG4⁺ plasma cells histologically, with an IgG4⁺:total IgG⁺ plasma cell ratio of >40%. This study investigated whether ECSs with CP and/or inflammatory disease in several organs show an increase in IgG4⁺ plasma cells within affected tissues. Histological sections of pancreas, liver, kidney, salivary gland and conjunctiva were obtained from ECSs with idiopathic chronic inflammatory disease affecting those tissues. Tissue samples from age-matched dogs of other breeds with similar diseases were also sampled. Control diseased tissue samples, from dogs without a suspected immune-mediated disease, were included. A subset of ECSs and dogs of other breeds presented with disease in more than one organ. Immunohistochemistry was performed with primary reagents detecting total IgG and three of the four canine IgG subclasses (IgG2, IgG3 and IgG4). Normal sections of pancreas and liver showed an absence of labelled plasma cells of any subclass. Normal kidney and salivary gland sections showed the presence of a few labelled plasma cells (<10 plasma cells/high-power field). Fourteen tissue sections from 12 ECSs and seven sections from six dogs of other breeds showed elevated numbers of IgG4⁺ plasma cells and IgG4⁺:IgG⁺ ratios >40%. Individual dogs (ECSs and other breeds) showed marked increases in IgG4⁺ cells. There were no significant differences in the number of IgG4⁺ plasma cells between ECSs and dogs of other breeds for affected pancreas, liver, salivary glands and conjunctiva. Kidney sections had more IgG4⁺ cells, for both ECSs and dogs of other breeds, than did sections from other organs. Dogs of other breeds had significantly more IgG4⁺ plasma cells in affected kidneys than ECSs. In conclusion, several ECSs and dogs of other breeds fulfilled the histological criteria for the diagnosis of IgG4-RD, supporting the existence of a multiorgan immune-mediated disease in ECSs and some dogs of other breeds.

IgG4-related skin disease may have distinct systemic manifestations: a systematic review

IgG4-related disease (IgG4-RD) is an increasingly prevalent protean multisystem disorder characterized by single or multi-organ infiltration of IgG4-bearing plasma cells. Skin involvement has been recognized and is relevant to proper diagnosis. A systematic literature review of 50 cases involving the skin reveals that patients with IgG4-related skin disease show predominant involvement of the head and neck and have a distinct pattern of systemic involvement, also favoring the head and neck - lymphatics, orbit, salivary, and lacrimal glands - but generally lacking pancreaticobiliary involvement (16% of cases), which by contrast is a predominant manifestation in systemic IgG4-RD (60% with pancreaticobiliary involvement). We summarize clinical and pathologic descriptive data from this systematic review. We review differential diagnosis and propose a diagnostic scheme for stratifying probability of disease based upon comprehensive integration of clinical, histopathologic, and laboratory data. Plasmacyte infiltration and storiform fibrosis are prominent in IgG4-related skin disease, but obliterative venulitis is less common than in the prototypical IgG4-related disease manifestation of autoimmune pancreatitis. IgG4 tissue and serum values, with a mean (±95% CI) in the reviewed cases of 132.8 ± 32.6 IgG4-positive plasma cells per high-power field and 580 ± 183.8 mg/dl, respectively, are incorporated into the suggested criteria. The distinct set of manifestations identified by this systematic review and the proposed diagnostic considerations, while requiring further validation in prospective studies, highlight the need to consider that IgG4-related skin disease defines a unique systemic disease complex along the spectrum of IgG4-RD.

Imaging of IgG4-related disease of the head and neck

IgG4-related disease is a systemic, inflammatory disorder typically involving multiple organ systems. Several eponymous conditions described previously in the clinical and radiology literature are now recognised to be part of the IgG4-related disease spectrum. This includes multiple manifestations in the head and neck region, which are the subject of this review. Imaging can occasionally suggest the specific diagnosis of IgG4 disease. More commonly, it will be included in a limited differential diagnosis that requires clarification with the aid of image-guided biopsy. There are strict histopathological criteria for the diagnosis of IgG4-related disease.

Immunoglobulin G4 related chronic sclerosing sialadenitis

Background:

ENT surgeons may be the first specialists to encounter and diagnose patients with salivary gland disease. A new entity involving the salivary glands has recently been described of which ENT surgeons need to be aware: immunoglobulin G4 related chronic sclerosing sialadenitis.

Method:

A literature search of Medline, Embase and Cochrane Library databases was performed, using the search terms ‘IgG4’, ‘hyperIgG4 syndrome’ and ‘IgG4 related chronic sclerosing sialadenitis’.

Results:

Knowledge concerning immunoglobulin G4 related chronic sclerosing sialadenitis is rapidly increasing. This new entity is part of a fibro-inflammatory corticosteroid-responsive systemic disease (immunoglobulin G4 related disease) and has been described in almost every organ. Biopsy of the submandibular gland can be diagnostic. However, the diagnosis can easily be overlooked if: clinical suspicion is not high, one is unaware of the classical morphology and/or immunoglobulin G4 staining is not performed. This paper presents a summary of the current understanding of the disease and its management.

Conclusion:

ENT surgeons should be aware of this new disease entity. Patients with systemic disease should be managed under a multidisciplinary team, with input from clinicians who have an interest in such diseases (such as gastroenterologists and rheumatologists), and input from histopathologists and radiologists.

Intraduct papillary mucinous neoplasm of the pancreas: a tumour linked with IgG4-related disease?

Objectives

Intraduct papillary mucinous neoplasm (IPMN) is a pancreatic tumour that is often associated with chronic pancreatitis (CP) in the surrounding pancreas. Type 1 autoimmune pancreatitis (AIP) is a fibro-inflammatory condition with characteristic histological features and prominent IgG4+ plasma cells and is part of the spectrum of IgG4-related disease (IgG4-RD). The aim of this study was to determine whether CP associated with pancreatic IPMN commonly represents AIP.

Methods

We identified two consecutive ‘index’ cases of pancreatic IPMN during routine reporting in which the adjacent pancreas showed morphological features suggestive of AIP. These cases were investigated using the Boston criteria for the histopathological diagnosis of IgG4-RD and the HISORt criteria for the clinical and histopathological diagnosis of AIP. Using the same criteria, we proceeded to a clinical review of 12 extra cases of IPMN in which the tumour or the surrounding pancreas showed significant lymphoplasmacytic inflammation and/or fibrosis.

Results

Both of the ‘index’ cases fulfilled the HISORt criteria for AIP and both had morphological features characteristic of IgG4-RD using the Boston criteria, although only one possessed features ‘highly suggestive of IgG4-RD’ after immunohistochemistry. Additionally, both ‘index’ cases had radiological features that could represent extrapancreatic manifestations. Review of the 12 additional cases of IPMN revealed no further examples showing co-existent AIP.

Conclusion

While pancreatic IPMN and AIP may co-exist, most CP associated with IPMN does not represent AIP.