IgG4-related sclerosing disease, an emerging entity: a review of a multi-system disease

The S228P mutation prevents in vivo and in vitro IgG4 Fab-arm exchange as demonstrated using a combination of novel quantitative immunoassays and physiological matrix preparation

Human immunoglobulin G isotype 4 (IgG4) antibodies (Abs) are potential candidates for immunotherapy when reduced effector functions are desirable. IgG4 Abs are dynamic molecules able to undergo a process known as Fab arm exchange (FAE). This results in functionally monovalent, bispecific antibodies (bsAbs) with unknown specificity and hence, potentially, reduced therapeutic efficacy. IgG4 FAE is suggested to be an important biological mechanism that provides the basis for the anti-inflammatory activity attributed to IgG4 Abs. To date, the mechanism of FAE is not entirely understood and studies measuring FAE in ex vivo matrices have been hampered by the presence and abundance of endogenous IgG4 wild-type (WT) Abs. Using representative humanized WT IgG4 monoclonal Abs, namely, anti-IL-6 and anti-TNF, and a core-hinge stabilized serine 228 to proline (S228P) anti-IL-6 IgG4 mutant, it is demonstrated for the first time how anti-IgG4 affinity chromatography can be used to prepare physiologically relevant matrices for assessing and quantifying FAE. A novel method for quantifying FAE using a single MSD immunoassay is also reported and confirms previous findings that, dependent on the redox conditions, the S228P mutation can prevent IgG4 FAE to undetectable levels both in vitro and in vivo. Together, the findings and novel methodologies will allow researchers to monitor and quantify FAE of their own IgG4 molecules in physiologically relevant matrices.

Riedel's Thyroiditis in an Elderly Male Patient: A Rare Entity

Riedel's thyroiditis (RT) is a rare fibrosclerotic infiltrative thyroid disorder of unclear aetiology. It has been reported in 0.06% of thyroid surgeries and is more common in women. A 60-year-old euthyroid male presented with thyroid swelling and sinus discharge since three years, associated with pain and fever. Near total thyroidectomy revealed right lobe measuring 5x2.5x2 cm, well encapsulated, firm to hard with resistance on cutting. Microscopic examination showed variable sized colloid filled follicles with intervening areas of dense fibrosis admixed with lymphocytic aggregates and perivascular fibrosis extending to the thyroid capsule. The diagnosis of Riedel's thyroiditis was made on histopathological examination. Hence, we would like to emphasize that Riedel's thyroiditis requires diagnostic thyroidectomy and histopathological examination for confirmation.

[Orbital inflammation]

Orbital inflammation is a generic term encompassing inflammatory pathologies affecting all structures within the orbit : anterior (involvement up to the posterior aspect of the globe), diffuse (involvement of intra- and/or extraconal fat), apical (involvement of the posterior orbit), myositis (involvement of only the extraocular muscles), dacryoadenitis (involvement of the lacrimal gland). We distinguish between specific inflammation and non-specific inflammation, commonly referred to as idiopathic inflammation. Specific orbital inflammation corresponds to a secondary localization of a "generalized" disease (systemic or auto-immune). Idiopathic orbital inflammation corresponds to uniquely orbital inflammation without generalized disease, and thus an unknown etiology. At the top of the differential diagnosis for specific or idiopathic orbital inflammation are malignant tumors, represented most commonly in the adult by lympho-proliferative syndromes and metastases. Treatment of specific orbital inflammation begins with treatment of the underlying disease. For idiopathic orbital inflammation, treatment (most often corticosteroids) is indicated above all in cases of visual loss due to optic neuropathy, in the presence of pain or oculomotor palsy.

Retroperitoneal disorders associated with IgG4-related autoimmune pancreatitis

IgG4-related autoimmune pancreatitis is frequently accompanied by relevant lesions in the genitourinary tract and retroperitoneal organs, which cause various clinical problems, ranging from non-specific back pain or bladder outlet obstruction to renal failure. The diagnosis of IgG4-related retroperitoneal fibrosis requires a multidisciplinary approach, including serological tests, histological examination, imaging analysis, and susceptibility to steroid therapy. Radiological examinations are helpful to diagnose this condition, but surgical resection is occasionally unavoidable to exclude malignancy, particularly for patients with isolated retroperitoneal involvement. Steroid therapy is the treatment of choice for this condition, the same as for other manifestations of IgG4-related disease. For patients with severe ureteral obstruction, additional ureteral stenting needs to be considered prior to steroid therapy to preserve the renal function. Some papers have suggested that IgG4-related disease can affect male reproductive organs including the prostate and testis. IgG4-related prostatitis usually causes lower urinary tract symptoms, such as dysuria and pollakisuria. Patients sometimes state that corticosteroids given for IgG4-related disease at other sites relieve their lower urinary tract symptoms, which leads us to suspect prostatic involvement in this condition. Because of the limited number of publications available, further studies are warranted to better characterize IgG4-related disease in male reproductive organs.

Value of serum IgG4 in differential diagnosis of IgG4-related disease from other autoimmune diseases

AIM: To investigate the value of serum IgG4 in differential diagnosis of IgG4-related disease (IgG4-RD) from other autoimmune diseases (AIDs).

METHODS: Clinical data for 15 patients with IgG4-RD and 187 patients with other autoimmune diseases who were treated at the First Affiliated Hospital of Fujian Medical University from July 2012 to February 2014 were retrospectively. Other AIDs included autoimmune hepatitis (AIH, n = 29), systemic lupus erythematosus (SLE, n = 30), rheumatoid arthritis (RA, n = 32), Sjögren syndrome (SS, n = 26), dermatomyositis (n = 13), adult onset still disease (n = 4), ankylosing spondylitis (AS, n = 15), systemic sclerosis (Scl, n = 11), and microscopic polyangiitis (n = 27). Serum IgG and IgG4 levels were measured with a rate nephelometer. ROC curves were then constructed to identify the optimal serum IgG4 cutoff value for diagnosing IgG4-RD and evaluating its sensitivity and specificity.

RESULTS: The median level of serum IgG4 in patients with IgG4-RD was 3.85 g/L (2.99-9.98 g/L), significantly higher than those in patients with other AIDs (P < 0.01). Serum IgG4 level was the highest in AS among groups of other AIDs (P < 0.01). Serum IgG4 levels were above 1.35 g/L in IgG4-RD patients. Elevated serum IgG4 levels were also observed in more than 10% of patients with AS, Scl and polyangiitis. The optimal cutoff value for the diagnosis of IgG4-RD was 2.09 g/L, and the sensitivity and specificity were 100% and 97.69%, respectively. The area under the curve (AUC) was 0.998. In all groups with other AIDs, the elevation rate of serum IgG4 level was less than 10% when the cutoff point was set at equal to or more than 2.09 g/L. Thus, the specificity of serum IgG4 was greatly improved.

CONCLUSION: Elevated serum IgG4 levels are observed in not only patients with IgG4-RD but also those with other AIDs. Using a cutoff point of 2.09 g/L, serum IgG4 could better differentiate IgG4-RD from other AIDs.

IgG4-related Hashimoto's thyroiditis--a new variant of a well known disease

Hashimoto's thyroiditis (HT) has been characterized for many years as a well-defined clinicopathologic entity, but is now considered a heterogeneous disease. IgG4-related HT is a new subtype characterized by thyroid inflammation rich in IgG4-positive plasma cells and marked fibrosis. It may be part of the systemic IgG4-related disease. We report a case of a 56-year-old Portuguese man who presented with a one-month history of progressive neck swelling and dysphagia. Laboratory testing revealed increased inflammatory parameters, subclinical hypothyroidism and very high levels of thyroid autoantibodies. Cervical ultrasound (US) demonstrated an enlarged and heterogeneous thyroid gland and two hypoechoic nodules. US-guided fine needle aspiration cytology was consistent with lymphocytic thyroiditis. The patient was submitted to total thyroidectomy and microscopic examination identified typical findings of HT, marked fibrosis limited within the thyroid capsule and lymphoplasmacytic infiltration, with >50 IgG4-positive plasma cells per high-power field and an IgG4/IgG ratio of >40%. After surgery, serum IgG4 concentration was high-normal. Symptoms relief and reduction in laboratory inflammatory parameters were noticed. Thyroid function is controlled with levothyroxine. To our knowledge we report the first case of IgG4-related HT in a non-Asian patient. We also perform a review of the literature regarding IgG4-related disease and IgG4-related HT. Our case highlights this new variant of the well known HT, and helps physicians in recognizing its main clinical features, allowing for proper diagnosis and treatment.

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.

Serum trypsin and TCR as novel markers for predicting disease activity in IgG4-related disease

Background

IgG4-related disease (IgG4-RD) is a novel disease named in recent years. Because of its varied clinical manifestations, like tumor but not tumor, it brings a great challenge to clinical diagnosis. Trypsin and T-cell receptor (TCR) are thought to mediate the regulation of B cell maturation, survival and antibody production. In this study, we investigated the clinical features and important novel markers of IgG4-RD.

Material and methods

A prospective cohort study of 22 patients with IgG4-RD was carried out from May 2009 to December 2012, and 65 cases with acute pancreatitis, 60 cases with pancreatic cancer and 120 healthy individuals were studied as controls. Serum TCR, trypsin and IgG4 levels were measured during pre- and post-treatment in the patients with IgG4-RD and their correlations with IgG4 were also assessed.

Results

Serum IgG4 and IgE levels in all patients were significantly increased, and tumor markers (carbohydrate antigen 19-9 and/or carbohydrate antigen 125) were also increased (12/22). Serum trypsin in patients with IgG4-RD was lower than in the ones with acute pancreatitis, pancreatic cancer, and healthy individuals. But serum TCR of IgG4-RD was significantly higher than in the pancreatic cancer group and normal controls and it was inversely correlated with the levels of IgG4 (r = –3.160, p = 0.042).

Conclusions

The results indicate that serum TCR and trypsin might be useful markers for predicting disease activity in IgG4-RD.

[Autoimmune pancreatitis in a patient with ulcerative colitis simulating a pancreatic tumor]

Pancreatic endocrine and/or exocrine functional disorders can be commonly detected in patients with inflammatory bowel diseases. Autoimmune pancreatitis is a rare disease and its co-existence with inflammatory bowel disease has been rarely reported. The diagnosis of autoimmune pancreatitis is difficult due to variable nonspecific symptoms, and the high rate of asymptomatic cases. The conventional imaging scans (ultrasonography, computed tomography, retrograde cholangiography) are usually not sensitive enough and they are frequently not able to differentiate between inflammatory and malignant tumorous diseases of the pancreas. The authors present the case history of a patient who developed both ulcerative colitis and autoimmune pancreatitis. The morphological changes of the pancreas detected by ultrasonography suggested the presence of pancreatic cancer, and this diagnosis was supported by the elevated level of serum CA19-9. Computed tomography failed to identify abnormalities in the pancreas and, finally, endoscopic ultrasound combined with fine needle aspiration cytology confirmed the diagnosis of autoimmune pancreatitis.

IgG4-Related Intracranial Hypertrophic Pachymeningitis : A Case Report and Review of the Literature

Hypertrophic pachymeningitis is an uncommon disorder that causes a localized or diffuse thickening of the dura mater. Recently, the possibility that IgG4-related sclerosing disease may underlie some cases of intracranial hypertrophic pachymeningitis has been suggested. We herein report the tenth case of IgG4-related intracranial hypertrophic pachymeningitis and review the previous literature. A 45-year-old male presented with left-sided focal seizures with generalization. Magnetic resonance imaging (MRI) revealed a diffuse thickening and enhancement of the right convexity dura matter and falx with focal nodularity. The surgically resected specimens exhibited the proliferation of fibroblast-like spindle cells and an infiltration of mononuclear cells, including predominantly plasma cells. The ratio of IgG4-positive plasma cells to the overall IgG-positive cells was 45% in the area containing the highest infiltration of plasma cells. On the basis of the above findings, IgG4-related sclerosing disease arising from the dura mater was suspected. IgG4-related sclerosing disease should be added to the pachymeningitis spectrum.

A Retrospectively Diagnosed Case of IgG4-Related Tubulointerstitial Nephritis Showing Good Renal Outcome and Pathological Progress

A 74-year-old man was hospitalized for diabetic nephropathy evaluation and assessment of the effect of treatment on his tubulointerstitial nephritis (TIN). When he was 62 years old, he developed polyarthralgia and had superficial lymph node swelling, mildly increased serum creatinine concentration, hypergammaglobulinemia, hypocomplementemia, high serum IL-2R level, and positive titer of antinuclear antibody. Several tissues were biopsied. Mild chronic sialadenitis and reactive lymphadenitis were identified. Renal specimen showed mild glomerular ischemia, extensive storiform fibrosis, and abundant infiltrating monocytes and plasma cells. He was treated with oral prednisolone and cyclophosphamide. After the treatment, most of his clinical parameters quickly returned to within the reference range. However, he developed diabetes mellitus soon after steroid therapy. At the time of rebiopsy, a high level of serum IgG4 was detected. The second renal biopsy showed diabetic nephropathy without any tubulointerstitial damage. The first biopsied tissues were retrospectively investigated. Large numbers of IgG4-positive plasma cells were detected in the kidneys and lymph nodes. A retrospective diagnosis of IgG4-related TIN with lymph node involvement was made. In conclusion, this paper describes a retrospectively diagnosed case of IgG4-related TIN with lymph node involvement, showing good clinical and pathological prognosis.

Orbital immunoglobulin-G4-related disease: case series and literature review

Immunoglobulin-G4-related disease (IgG4-RD) is a distinct group of diseases characterized by elevated serum IgG4 titres and infiltration of affected organs by IgG4-positive plasma cells. IgG4-RD can involve any ocular adnexal tissue. They have a distinct prognosis and pattern of tissue involvement and hence need to be differentiated from orbital lesions with similar clinicopathological features. We report three cases of IgG4-RD and review the literature extensively discussing various aspects of this novel entity.

Small bowel obstruction caused by peritoneal immunoglobulin g4-related disease mimicking carcinomatosis: case report

We hereby report a case of diffuse pelvic peritoneal involvement by immunoglobulin G4-related disease (IgG4-RD). Numerous pelvic masses and nodules showing delayed enhancement on enhanced abdominal CT were found to congregate in the pelvic organs of a 57-year-old female presenting with intestinal subocclusion. The differentiation between peritoneal IgG4-RD and pelvic peritoneal carcinomatosis was only made by histopathology and immunohistochemistry performed after surgical resection. Autoimmune pancreatitis represents the historical prototype of IgG4-RD, but the spectrum of manifestations involving various organs has expanded during the last decade. In this report, we shortly review this clinical entity.

A Case Report of IgG4-Related Disease Clinically Mimicking Pleural Mesothelioma

An immunoglobulin G4 (IgG4)-related disease is a recently emerging entity, and a few cases of IgG4-related disease in lung and pleura have been reported. Herein, we report the case of a 74-year-old man with IgG4-related disease of lung and pleura, clinically suspicious of malignant mesothelioma. Chest computed tomography showed diffuse nodular pleural thickening, and microscopic finding disclosed diffuse thickening of visceral pleura with infiltrations of many lymphoplasma cells with increased number of IgG4-positive plasma cells and a few multinucleated giant cells. It is important for pathologists and clinicians to recognize this rare entity and its histologic finding, because it can be confused with malignant tumors on the radiologic examination although it can be treated with steroid therapy.

IgG4-related orbital disease: a meta-analysis and review

IgG4-related orbital disease (IgG4-ROD) is a recently described condition that may account for a significant proportion of idiopathic lymphoplasmacytic or sclerotic orbital lesions. This study is the first meta-analysis of published cases and reveals several differences between IgG4-related disease affecting the orbit and that affecting the pancreas. IgG4-ROD affects a slightly younger group of patients, affects men and women approximately equally, is commonly associated with salivary gland lesions, is associated with a relatively higher serum IgG4 and may confer an increased risk of non-Hodgkin Lymphoma. Its pathogenesis may involve an immune response to antigen exposure in the upper aerodigestive tract.

Immunoglobulin G4-related sclerosing disease with orbital inflammation in a 12-year-old girl

Immunoglobulin G4-related sclerosing disease is a rare but potentially debilitating cause of orbital inflammation, with a predilection for older males. We report the case of a 12-year-old African girl with immunoglobulin G4-related sclerosing disease, including possible extraorbital involvement. Because of an escalating severity of illness leading to oculomotor nerve palsy and cavernous sinus thrombosis that was resistant to steroids, systemic immunosuppressive therapy with rituximab was used to achieve disease remission. The diagnosis was histologically confirmed with a tissue biopsy.

The spectrum of IgG4-related disease in the abdomen and pelvis

OBJECTIVE

IgG4-related disease was not recognized as a specific clinical entity until 2003 when extrapancreatic lesions were reported in patients with autoimmune pancreatitis. IgG4-related disease is characterized by elevated serum IgG4 levels and infiltration of the target organ by IgG4-positive plasma cells. The complete gamut of visceral involvement is still being outlined. The purpose of this article is to highlight the plethora of lesions under the spectrum of IgG4-related disease of the abdomen and pelvis, describe their imaging appearances on multimodality cross-sectional imaging, and discuss the differential diagnoses.

CONCLUSION

It is important for radiologists to recognize the multiorgan involvement and few classic features of IgG4-related disease that often tend to simulate malignancy.

[A case of IgG4 associated sclerosing cholangitis without clinical manifestations of autoimmune pancreatitis]

IgG4-related systemic diseases are characterized by a diffuse or mass forming inflammatory reaction rich in lymphocytes and IgG4-positive plasma cells (lymphoplasmacytic infiltration), fibrosclerosis of variable organs and obliterative phlebitis. They usually involve various organs including the pancreas, bile duct, gallbladder, salivary gland, retroperitoneum, kidney, lung, and prostate. However, most of them are accompanied by autoimmune pancreatitis, and good response to steroid treatment is one of the hallmarks of this disease. We report a case of an 67-year-old man with IgG4 associated sclerosing cholangitis, who was diagnosed by endoscopic retrograde cholangiopancreatography and successfully treated with steroid therapy.

Lymphoplasmacytic hypophysitis associated with immunoglobulin G4

We present the unusual case of a 33-year-old woman who presented with a 2 year history of amenorrhoea and an expanding sellar lesion. Initial MRI revealed a lesion in the pituitary fossa, thought to be a pituitary adenoma. One year later, the lesion had enlarged by 5mm, with associated enhancement of the dura of the planum sphenoidale and pituitary stalk. Histopathology revealed a lymphocytic and plasma cell inflammatory infiltrate suggestive of lymphoplasmacytic hypophysitis associated with immunoglobulin G4.

Measurement of serum IgG4 levels by an established ELISA system and its clinical applications in autoimmune diseases

IgG4-related disease (IgG4-RD) is a novel and rare autoimmune disease entity. Elevated serum IgG4 level is strongly suggestive of IgG4-RD. But it is still unknown whether serum IgG4 elevation commonly occurs in other autoimmune diseases. In this study, the serum IgG4 levels were detected by an established enzyme-linked immunosorbent assay (ELISA) in a variety of autoimmune diseases including systemic lupus erythematosus (SLE), Sjogren's syndrome (SS), polymyositis or dermatomyositis (PM/DM) and IgG4-RD. To evaluate the reliability of this ELISA system, some of our samples were sent to a lab in Kanazawa Medical University, Japan, and detected by using the nephelometric assay. The results showed that our findings were consistent with theirs. Moreover, it was found that the serum IgG4 levels were 0.23±0.16 g/L in 53 healthy controls, 0.16±0.15 g/L in 103 SLE patients, 0.22±0.18 g/L in 41 SS patients and 0.40±0.32 g/L in 21 PM/DM patients. No significant difference in the serum IgG4 level was observed among these groups (P>0.05). The serum IgG4 levels of two cases of IgG4-RD were 1.63 and 4.65 g/L respectively, and both decreased markedly after treatment with glucocorticoids. These data indicated that this established ELISA system can be used for detecting serum IgG4 levels. Elevated serum IgG4 levels help diagnose IgG4-RD and evaluate the curative effect of this condition rather than other autoimmune diseases.

Interstitial cystitis: another IgG4-related inflammatory disease?

Interstitial cystitis (IC) is a disease of undetermined etiology and pathogenesis. Inflammation is thought to play a key role in many patients, characteristically with an increase in mast cells within the detrusor muscle of the bladder. We observed that some patients with IC had prominent plasma cells in bladder tissue, which elicited our interest in their possible pathogenic role in patients with IC. A total of 44 cases of IC were collected, including 42 bladder biopsies and 2 cystectomies. Patient age ranged from 18 to 92 years (average age of 49.5 years) and included 7 male and 37 female patients. The histology and immunostains for IgG, IgG4 and tryptase were examined, and the results were correlated with clinical and cystoscopic findings. Four cases showed a significant increase in IgG4-positive plasma cells, with greater than 30 IgG4 plasma cells per high-power field and an IgG4/IgG ratio greater than 0.5. In addition, statistically significant differences were found between IC with IgG4-positive plasma cells vs IgG4-negative cases. The IgG4-positive patients were of older age and had increased severe inflammation and decreased bladder capacity as compared with the IgG4-negative patients. We propose that a subset of patients with IC may have an IgG4-related disease, and further study including serum IgG4 measurement is required to better define this relationship.

Riedel thyroiditis in a patient with graves disease

Riedel's thyroiditis is a rare form of infiltrative and inflammatory disease of the thyroid gland and can be associated with systemic fibrotic processes, Hashimoto thyroiditis and Graves disease. Riedel thyroiditis in combination with Graves disease however, is very rare. A 57-year-old woman with a past medical history significant for Graves disease diagnosed 30 years ago presented with an enlarging neck mass and voice changes. Due to suspicion of malignancy, thyroidectomy was performed. Histopathologic examination revealed Riedel thyroiditis. To our knowledge, the association of Riedel thyroiditis with Graves disease has not yet been reported in our country. Here we report a patient with Riedel thyroiditis evolved from antecedent Graves disease.

IgG4-related multiorgan disease: report of the first autopsy case

IgG4-related disease (IgG4RD) is a chronic recurring fibro-inflammatory pathology that is considered to be of autoimmune origin. Histopathology is considered to be the gold standard method for diagnosis. IgG4RD affects multiple organs. IgG4RD was first identified in the pancreas and was called autoimmune pancreatitis (AIP). During the following years, the disease spectrum was expanded and it was realised that the extrapancreatic lesions can precede, coexist or appear after the diagnosis of AIP. At present, several illnesses such as Mikulicz disease, Küttner tumour, multifocal fibrosclerosis, etc, are considered to be part of the IgG4RD spectrum. The symptoms of the disease tend to appear over months and years and diagnosis is achieved on average 13.5 months (4-60 months) after the onset. The purpose of this report was to provide information about a case that was sadly fatal but that permitted a complete histopathological study of the damaged tissues.

IgG4-related disease of the head and neck

IgG4-related disease is an uncommon sclerosing and inflammatory mass-forming disease that may affect a single organ or be systemic. The prototypical example of the disease is type 1 autoimmune pancreatitis. After the pancreatobiliary system, the head and neck is the next most common site for involvement by IgG4-related disease. Here, we describe the clinicopathologic features of the head and neck involvement by this disease process with particular attention to involvement of the major salivary glands, the lacrimal glands and periorbital tissues, the upper aerodigestive tract, the thyroid gland, lymph nodes, the ear, and the skin and soft tissues.

Autoimmune cholangitis and cholangiocarcinoma

Autoimmune cholangitis, immunoglobulin G4-associated cholangitis (IAC), is a part of multiorgan IgG4-related systemic disease, which was recognized as a new clinicopathological entity in recent years. IAC is defined as a biliary stricture that responds to steroid therapy, frequently is associated with other fibrosing conditions, especially autoimmune pancreatitis and is characterized by elevation of IgG4 in serum and infiltration of IgG4 positive plasma cells in bile ducts. Since IAC shares a number of clinical, biochemical, and imaging features with cholangiocarcinoma (CCA), it is often misdiagnosed as CCA, and unnecessary surgery was performed. In this compact review, we clarify the disease of IAC, summarize criteria for diagnosis of IAC, discuss the role of CA 19-9, and provide key information to differentiate diagnosis of IAC from CCA. IAC should be highly suspected in unexplained biliary stricture associated with increased IgG4 (in serum especially in bile) and other organ involvement (kidney, retroperitoneum etc. especially pancreas in which there are abundant IgG4-positive plasmocytes infiltration). Correct diagnosis of IAC will avoid unnecessary surgery because IAC responds well to steroid therapy. In a word, increased IgG4 levels, other organ involvement and response to steroids are keys to distinguishing IAC from CCA.

Urethral caruncle: a lesion related to IgG4-associated sclerosing disease?

Aims

Urethral caruncle is a benign, polypoid urethral mass that occurs almost exclusively in postmenopausal women. Despite that these lesions are routinely managed with topical medications or excision, their pathogenesis is not well understood. We investigated the possibilities of autoimmune, viral and inflammatory myofibroblastic proliferations as possible aetiologies.

Methods

In 38 patients with urethral caruncle, we utilised immunohistochemistry for immunoglobulin G (IgG) and IgG4 to assess for a potential autoimmune aetiology. Immunohistochemistry was performed in nine patients for Epstein–Barr virus, BK virus, human herpesvirus 8, human papillomavirus, adenovirus and anaplastic lymphoma kinase.

Results

Four patients (11%) showed infiltrates of ≥50 IgG4-positive plasma cells per high power field, of which all showed an IgG4 to IgG ratio greater than 40%. A statistically significant difference (p<0.01) was detected in the mean number of IgG4-positive cells (14.73 per high power field) compared with control benign urethral specimens (mean, 1.19). One patient with increased counts below this threshold had rheumatoid arthritis; none had documented autoimmune pancreatitis or other known manifestations of systemic IgG4-related sclerosing disease. All lesions showed negative reactions for the viral and inflammatory myofibroblastic markers.

Conclusions

Urethral caruncle is a benign inflammatory and fibrous polypoid urethral mass of unclear aetiology. It appears unrelated to viral infection and lacks the abnormal expression of anaplastic lymphoma kinase protein, as seen in inflammatory myofibroblastic tumours. Increased numbers of IgG4-positive plasma cells in a subset of lesions raise the possibility that some cases may be related to the autoimmune phenomena of IgG4-associated disease.

18F-fluoro-deoxyglucose positron emission tomography/computed tomography scan findings in Rosai-Dorfman disease with IgG4-positive plasma cell infiltration mimicking breast malignancy: a case report and literature review

INTRODUCTION

Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a rare benign disorder characterized histologically by lymphatic sinus dilatation due to histiocyte proliferation. Rosai-Dorfman disease accompanied by IgG4+ plasma cell infiltration is an even rarer situation. To the best of our knowledge, no imaging report of fluoro-deoxyglucose positron emission tomography/computed tomography findings of Rosai-Dorfman disease with IgG4+ plasma cell infiltration has been published, although a series of pathological research has focused on this phenomenon.

CASE PRESENTATION

We reviewed the 18F-fluoro-deoxyglucose positron emission tomography/computed tomography scan of a 78-year-old Chinese woman with a solid mass that was found in her right breast during a health checkup. 18F-fluoro-deoxyglucose positron emission tomography/computed tomography showed a hypermetabolic nodule in her right breast and slightly heterogeneous increased fluoro-deoxyglucose uptake of the pulmonary nodules, which were histologically proven to be mammary Rosai-Dorfman disease with IgG4+ plasma cell infiltration and pulmonary amyloidosis, respectively. A literature review was performed to gather information on this rare disease process.

CONCLUSIONS

Although distinguishing benign lymphoplasmacytic proliferation from malignancy may be difficult with 18F-fluoro-deoxyglucose positron emission tomography/computed tomography in light of the pattern and intensity of fluoro-deoxyglucose uptake, our case highlights that whole-body positron emission tomography/computed tomography imaging not only can display the extent of the disease to help complete staging but also can provide functional information about disease activity to guide biopsy.

Recent advances in research of immunoglobulin G4-related sclerosing cholangitis

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is a recently defined disease entity characterized by elevated serum IgG4, chronic progressive obstructive jaundice, and diffuse or mass-forming inflammatory reaction rich in IgG4-positive plasma cells and lymphocytes associated with fibrosclerosis and obliterative phlebitis, which shares a number of clinical, biochemical, and radiological features with primary sclerosing cholangitis (PSC) or cholangiocarcinoma (CC). IgG4-SC is commonly associated with autoimmune pancreatitis (AIP). Steroid therapy comprises the mainstay of treatment for IgG4-SC patients. However, liver transplantation is the only useful treatment for PSC patients, and CC patients require surgical therapy. Therefore, the accurate discrimination between IgG4-SC and PSC or CC is a very important issue. In this article, we will review the features and role of immunoglobulin G4 (IgG4), the diagnosis and therapy of IgG4-SC, and the relations between IgG4-SC and AIP, PSC or CC.

IgG4-related disease and the current status of diagnostic approaches

IgG4-related disease is a newly recognized systemic disease characterized by involving a wide range of organs. It includes the pancreas, biliary tree, salivary glands, periorbital tissues, upper aerodigestive tract, retroperitoneum, mediastinum, aorta, soft tissue, skin, central nervous system, breast, kidneys, prostate, lungs and lymph nodes. The elevated serum titer of immunoglobulin G4 (IgG4), which is the least common (3 % to 6 %) of the 4 subclasses of IgG, is a special marker for IgG4-related disease. However, its entity is still unknown. This article reviewed the literature to learn the IgG4-related diseases and their current status of diagnostic approaches.

Diagnostic Dilemma in a Patient with Jaundice: How to Differentiate between Autoimmune Pancreatitis, Primary Sclerosing Cholangitis and Pancreas Carcinoma

A 68-year-old male patient was referred to our institution in May 2011 for a suspected tumor in the pancreatic head with consecutive jaundice. Using magnetic resonance imaging, further differentiation between chronic inflammation and a malignant process was not possible with certainty. Apart from cholestasis, laboratory studies showed increased values for CA 19-9 to 532 U/ml (normal <37 U/ml) and hypergammaglobulinemia (immunoglobulin G, IgG) of 19.3% (normal 8.0–15.8%) with an elevation of the IgG4 subtype to 2,350 mg/l (normal 52–1,250 mg/l). Endoscopic retrograde cholangiopancreatography revealed a prominent stenosis of the distal ductus hepaticus communis caused by pancreatic head swelling and also a bihilar stenosis of the main hepatic bile ducts. Cytology demonstrated inflammatory cells without evidence of malignancy. Under suspicion of autoimmune pancreatitis with IgG4-associated cholangitis, immunosuppressive therapy with steroids and azathioprine was started. Follow-up endoscopic retrograde cholangiopancreatography after 3 months displayed regressive development of the diverse stenoses. Jaundice had disappeared and blood values had returned to normal ranges. Moreover, no tumor of the pancreatic head was present in the magnetic resonance control images. Due to clinical and radiological similarities but a consecutive completely different prognosis and therapy, it is of fundamental importance to differentiate between pancreatic cancer and autoimmune pancreatitis. Especially, determination of serum IgG4 levels and associated bile duct lesions induced by inflammation should clarify the diagnosis of autoimmune pancreatitis and legitimate immunosuppressive therapy.