Pathological classification of hepatic inflammatory pseudotumor with respect to IgG4-related disease

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.

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.

Clinical features, image findings, and prognosis of inflammatory pseudotumor of the liver: a multicenter experience of 45 cases

Background/Aims

Inflammatory pseudotumor (IPT) of the liver is a rare disease characterized by chronic infiltration of inflammatory cells. However, the clinical characteristics and outcomes of IPT remain uncertain.

Methods

Clinical features, image findings, and outcomes of 55 patients with histologically proven IPT were evaluated.

Results

They consisted of 26 men and 19 women with median age of 65 years. Serum carcinoembryonal antigen and carbohydrate antigen 19-9 levels were normal in 42 patients (93.3%). Enhanced CT scans indicated poorly defined peripheral enhancement (82.5%) at the arterial phase and poorly defined hyperattenuating lesions with internal hypoattenuating areas at the equilibrium phase (77.0%). Gadolinium-enhancement MRI revealed poorly defined peripheral rim-like enhancement (77.8%). Ten patients underwent surgical resection and 35 were treated conservatively with or without antibiotics. No recurrence was noted after surgical resection during follow-up (1 to 48 months). In all patients who received conservative treatment, complete resolution or size reduction was noted during follow-up (1 to 192 months).

Conclusions

CT and MRI provide clues to the diagnosis of IPT in patients with liver masses and normal tumor markers. However, due to the lack of pathognomonic findings, the clinician's suspicion and histological diagnosis are necessary to make an accurate diagnosis of IPT.

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.

Immunoglobulin g4-related disease mimicking unresectable gallbladder cancer

Immunoglobulin G4 (IgG4)-related disease is a novel disease entity that can involve diverse organs, causing specific diseases, including autoimmune pancreatitis, sclerosing cholangitis, cholecystitis, inflammatory aortic aneurysm, and inflammatory pseudotumor. IgG4-related disease is characterized by elevated serum IgG4 concentrations, abundant IgG4 lymphoplasmacytic infiltration, and dramatic steroid responses. It is clinically important to differentiate this rare disease from primary sclerosing cholangitis and cholangiocarcinoma, because the treatment and prognosis of these two diseases are completely different. However, the preoperative diagnosis is challenging, and the disease is frequently misdiagnosed. If the serum level of IgG4 is within the normal range, the diagnosis of IgG4-related disease is more difficult. This article reports on a 59-year-old man with IgG4-related disease mimicking unresectable gallbladder cancer with normal serum IgG4 concentrations.

IgG4-related Disorders of the Gastrointestinal Tract

IgG4-related disease, a newly established multisystemic disease can affect virtually every organ. Histologically, it is characterized by the presence of a dense lymphoplasmacytic infiltrate, storiform-type fibrosis, and obliterative phlebitis. The disease shows elevated serum and tissue IgG4. The pancreas and hepatobiliary tract are involved far more commonly than the tubular gut. This review summarizes the clinical and pathologic features of the gastrointestinal manifestations of IgG4-related disease and discusses the wide spectrum of diseases that this entity may mimic.

A Case of Inflammatory Pseudotumor of the Liver Mimicking Hepatocellular Carcinoma on EOB-MRI and PET

A 71-year-old man was referred to us for investigation of a liver mass and adenomyomatosis of gallbladder. Findings on ethoxybenzyl diethylenetriamine-enhanced MRI (EOB-MRI) led to a presumptive diagnosis of a 1.5 cm hepatocellular carcinoma (HCC) in the right posterior lobe of the liver. Transcatheter arterial chemoembolization and radiofrequency ablation of the tumor were attempted. After 2 months, CT scan and EOB-MRI showed that the tumor had enlarged to 3 cm. Positron emission tomography (PET) confirmed abnormal metabolic activity with a high standardized uptake value of 7.3 in the lesion. These findings could indicate malignancy such as well-differentiated HCC or cholangiocarcinoma or a benign lesion such as hepatic abscess. Histopathological examination of a liver biopsy revealed a granuloma with many inflammatory cells, leading to a diagnosis of inflammatory pseudotumor of the liver. We report a rare case of hepatic inflammatory pseudotumor with enhancement on EOB-MRI and increased uptake on PET, mimicking HCC.

IgG4-related disease-like fibrosis as an indicator of IgG4-related lymphadenopathy

The significance of IgG4-related diseases including IgG4-related lymphadenopathy has recently been recognized worldwide. Inflammatory pseudotumors in lymph nodes, as well as in other organs, are also recognized as IgG4-related diseases. Only a few case reports have described IgG4-related lymphadenopathy with fibrosis (IgG4-fibrosing lymphadenopathy), and IgG4-fibrosing lymphadenopathy has not been compared clinicopathologically with non-IgG4-related lymphadenopathy with fibrosis. We have evaluated the pathologic features in 13 patients with IgG4-fibrosing lymphadenopathy, including IgG4 and IgG expression in lymph nodes, and compared these features with those of patients with non-IgG4-related lymphadenopathy with fibrosis with reactive inguinal lymphadenopathy and focal fibrosis and lymph nodes at least 10 mm in diameter. IgG4-fibrosing lymphadenopathy was characterized by lymphoplasmacytic and eosinophilic infiltration, many IgG4-positive plasma cells in fibrotic areas, and high serum IgG4 concentrations. The IgG4-positive/IgG-positive plasma cell ratio was significantly higher in the IgG4-fibrosing lymphadenopathy than in the non-IgG4-fibrosing lymphadenopathy group. The presence of even minor fibrosis with characteristics of IgG4-related disease such as IgG4-fibrosing lymphadenopathy may facilitate the diagnosis of IgG4-related lymphadenopathy.

Recurring multicystic inflammatory pseudotumor of the liver: a case report

Inflammatory pseudotumor (IPT) of the liver is a rare benign lesion for which imaging diagnosis remains a challenge. We report the case of a 39-year-old Algerian woman, who presented epigastric pains combined with fever and jaundice. Ultrasound, CT scan and MRI showed the presence of a 10 cm-long multi-septated cystic mass of the left lobe, with peripheral enhancement. A left-hepatectomy was performed and histopathology revealed an IPT of the liver. During the 4 following years, the patient had three other recurrences of liver IPT at various locations distinct from the original, revealed by the same clinical symptoms. During these relapses, the lesions did regress thanks to a medical treatment. This observation underlines the difficulty of the diagnosis and treatment of liver IPT.

A case of intraperitoneal immunoglobulin G4-related inflammatory pseudotumor

The term inflammatory pseudotumor (IPT) has been used to describe inflammatory and fibrosing tumoral processes of an undetermined cause that may involve a variety of organ system. IgG4-related disease is a newly recognized fibroinflammatory condition characterized by IgG4-producing plasma cell expansion in affected organs and, often but not always, elevated serum IgG4 concentrations. IgG4-related IPTs, a subtype of IPT, are characterized by dense infiltration of IgG4-positive plasma cells and stromal fibrosis. The association between inflammatory pseudotumor and IgG4 was first reported with a regard to sclerosing pancreatitis. Despite there are many reports on intraperitoneal IPTs including both cellular and lymphoplasmacytic type, only a few cases have been confirmed to be IgG4-related. We experienced a case of intraperitoneal IgG4-related inflammatory pseudotumor in an 83-year-old woman presenting with epigastric pain and malaise. Surgical specimens revealed an IgG4-related inflammatory pseudotumor.

Immunoglobulin G4-associated inflammatory pseudotumor of urinary bladder: a case report

A previously healthy 72-year old woman was admitted with a chief complaint of gross hematuria and fecaluria for 4 months. On initial computed tomographic examination, a lobulated shaped intravesical protruding mass with adhesion to the sigmoid colon was identified. Under a clinical diagnosis of bladder cancer with vesicosigmoid fistula vs sigmoid colon cancer with vesicosigmoid fistula, a frozen section evaluation of the bladder mass was performed to determine the origin of the tumor. Because the frozen section diagnosis of the bladder mass was an inflammatory origin, a partial cystectomy with segmental resection of the adherent sigmoid colon was elected. The microscopic examination of the partial resection of the urinary bladder revealed suburothelial inflammatory mass lesion, involving the entire wall of bladder with extension to the sigmoid colon, which was composed of spindle cells without significant atypia admixed with many lymphocytes, plasma cells, and some scattered eosinophils. Chronic inflammation around nerve bundles, sclerotic fibrosis, and prominent lymphoid follicles with plasma cells were the main features of the mass. No urothelial dysplasia or malignancy was seen. An average of 57 plasma cells per 1 high-power field was immunoreactive for immunoglobulin (Ig) G4 with IgG4/IgG ratio of more than 40%, a diagnostic feature of IgG4-associated inflammatory pseudotumor (IPT), arising in the bladder with the secondary involvement of the sigmoid colon. Recent studies reported many IPTs associated with IgG4 in other locations; however, to the best of our knowledge, IgG4-associated IPT in the urinary bladder has not been reported. We describe herein the first case of IgG4-associated IPT, lymphoplasmacytic type in the urinary bladder.

Inflammatory pseudotumors mimicking intrahepatic cholangiocarcinoma of the liver; IgG4-positivity and its clinical significance

BACKGROUND

Inflammatory pseudotumor (IPT) of the liver is a benign condition with a good prognosis. However, it is difficult to distinguish clinical and radiological findings of IPT from those of malignancies. The aims of this study are to determine the clinical, radiological, and pathological characteristics, particularly relating to the role of the autoimmune mechanism in the development of inflammatory pseudotumours (IPTs) of the liver, and to suggest appropriate diagnostic and therapeutic strategy.

STUDY DESIGN

The clinical, diagnostic, and pathological characteristics including IgG4 immunohistochemical stain and follow-up data of 22 IPT patients were retrospectively analyzed.

RESULTS

The patients were 16 men and 6 women with a mean age of 59 years. Fifteen patients (68.2%) had associated biliary diseases. Of the 16 patients treated conservatively, the masses completely resolved in 10 patients, and reduced in size in 5 patients within the first 6 months. The remaining 6 patients were treated by surgical resection. IgG4 staining of 17 tissue samples from 22 patients were negative, most of the infiltrate being of fibrohistiocytic type, whereas 4 of 5 lymphoplasmacytic cells of dominant tumors show positive staining of IgG4. Although IgG4-related sclerosing cholangitis was mostly of lymphoplasmacytic type, other histological and clinical characteristics were similar in both types of IPTs.

CONCLUSIONS

IPTs of the liver can be diagnosed based on radiological and pathological findings by needle biopsy. Although the lymphoplasmacytic type of IPTs seems to correspond to IgG4-related disease, as assessed by IgG4 immunohistochemical stain, its clinical significance is unknown. Although most IPTs can be resolved with conservative therapy, surgical resection should be considered in cases of uncertain biopsy result, presumed malignant lesion, combination with other pathology, or lack of response to conservative management.

Immunoglobulin G4-related sclerosing cholangitis: pathologic features and histologic mimics

Since immunoglobulin G4 (IgG4)-related sclerosing cholangitis was first described in 2004, this condition has been recognized as a distinct entity characterized by unique pathologic features. Affected bile ducts show diffuse wall thickening, which represents transmural sclerosing inflammation composed of a dense lymphoplasmacytic infiltrate and fibrosis arranged at least focally in a storiform pattern. A diffuse IgG4-positive plasma cell infiltrate is demonstrable by immunohistochemistry. More than 90% of patients with IgG4-related sclerosing cholangitis have type 1 autoimmune pancreatitis, the remaining presenting as isolated cholangitis. The diagnosis requires a multidisciplinary approach, in which pathologic examination has a critical role. Tissue diagnosis on biopsy specimens (ie, bile duct biopsy, liver needle biopsies) is important, particularly for patients with isolated cholangitis, given the fact that radiological findings of IgG4-cholangitis are not reliable enough for establishing the diagnosis. Furthermore, serum IgG4 levels can be, albeit mildly, elevated in other biliary disorders. Histologic mimics of IgG4-related sclerosing cholangitis include primary sclerosing cholangitis, follicular cholangitis, and sclerosing cholangitis with granulocytic epithelial lesion, the latter 2 being recently described entities.

IgG4-related disease: nomenclature, clinical features, and treatment

Concepts about IgG4-related disease (IgG4-RD) are now emerging swiftly. The condition has been identified in virtually every organ system, and its features are often excellent mimickers of malignancies, infections, and other immune-mediated disorders. Recommendations for nomenclature were proposed by the Organizing Committee of the 2011 International IgG4-related disease Symposium, and guidelines for the pathologic diagnosis of this condition have been published by an international group of experts. Experience with treatment regimens is growing. Glucocorticoids and B-cell depletion strategies both appear to be effective and are the subject of ongoing studies. This article reviews the current thought and understanding of this disease with regard to nomenclature, organ system involvement, and approaches to therapy.

Immunoglobulin G4-related sclerosing disease involving the urethra: case report

Immunoglobulin G4 (IgG4)-related sclerosing disease is a systemic disease characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration in various organs. We described the imaging findings of an IgG4-related inflammatory pseudotumor in the urethra. The urethral mass showed isoattenuation on unenhanced CT images, delayed enhancement on enhanced CT images, iso- to slight hyper-intensity on T1 and T2 weighted magnetic resonance images, diffusion restriction on diffusion weighted images, and heterogeneously low echogeneity on ultrasonography.

Inflammatory angiomyolipoma of the liver: a rare hepatic tumor

Angiomyolipoma (AML) is a rare mesenchymal neoplasm of the tumor, composed of a varying heterogeneous mixture of three tissue components: blood vessels, smooth muscle and adipose cells. Hepatic AML may demonstrate a marked histological diversity. We herein present one case of hepatic AML exhibiting prominent inflammatory cells in the background, which happened in a 61-year-old Chinese female patient, without signs of tuberous sclerosis. Histologically, the striking feature was the infiltration of numerous inflammatory cells in the background, including small lymphocytes, plasma cells, and eosnophils. The tumor cells were spindled and histiocytoid in shape, with slightly eosinophilic cytoplasm, and arranged along the vessels or scattered among the inflammatory background. Sinusoid structure was obviously seen in the tumor. Mature adipocytes and thick-walled blood vessels were focally observed at the boundaries between the tumor and surrounding liver tissues. The tumor cells were positive immunostaining for HMB-45, Melan-A, and smooth muscle actin. The inflammatory AML should be distinguished from other tumors with inflammatory background such as inflammatory myofibroblastic tumor and follicular dendritic cell tumor and deserves wider recognition for its occurrence as a primary hepatic tumor.

Consensus statement on the pathology of IgG4-related disease

IgG4-related disease is a newly recognized fibro-inflammatory condition characterized by several features: a tendency to form tumefactive lesions in multiple sites; a characteristic histopathological appearance; and-often but not always-elevated serum IgG4 concentrations. An international symposium on IgG4-related disease was held in Boston, MA, on 4-7 October 2011. The organizing committee comprising 35 IgG4-related disease experts from Japan, Korea, Hong Kong, the United Kingdom, Germany, Italy, Holland, Canada, and the United States, including the clinicians, pathologists, radiologists, and basic scientists. This group represents broad subspecialty expertise in pathology, rheumatology, gastroenterology, allergy, immunology, nephrology, pulmonary medicine, oncology, ophthalmology, and surgery. The histopathology of IgG4-related disease was a specific focus of the international symposium. The primary purpose of this statement is to provide practicing pathologists with a set of guidelines for the diagnosis of IgG4-related disease. The diagnosis of IgG4-related disease rests on the combined presence of the characteristic histopathological appearance and increased numbers of IgG4⁺ plasma cells. The critical histopathological features are a dense lymphoplasmacytic infiltrate, a storiform pattern of fibrosis, and obliterative phlebitis. We propose a terminology scheme for the diagnosis of IgG4-related disease that is based primarily on the morphological appearance on biopsy. Tissue IgG4 counts and IgG4:IgG ratios are secondary in importance. The guidelines proposed in this statement do not supplant careful clinicopathological correlation and sound clinical judgment. As the spectrum of this disease continues to expand, we advocate the use of strict criteria for accepting newly proposed entities or sites as components of the IgG4-related disease spectrum.

Diagnostic usefulness of precise examinations with intraductal ultrasonography, peroral cholangioscopy and laparoscopy of immunoglobulin G4-related sclerosing cholangitis

Herein, a case of immunoglobulin G4 (IgG4)-related sclerosing cholangitis is reported. IgG4 was diagnosed based on observations from peroral cholangioscopy and laparoscopy, and these methods are proposed for definitive and precise diagnosis of this disease. A 76-year-old male patient with inguinal Paget's disease had intrahepatic bile duct dilatations detected with computed tomography at his periodic check-up. Magnetic resonance cholangiography showed stenosis of the upper common bile duct and poststenotic dilatation of left intrahepatic bile ducts. The portal tract and bilateral intrahepatic bile ducts were surrounded by a low-density area, facing a tumor-like lesion at segment 2. Cytological examinations of the stenotic and dilated lesions revealed no cellular atypia. Histological examination of the tumor showed normal liver tissue with infiltration of lymphocytes, indicating an inflammatory pseudotumor. Peroral cholangioscopy excluded the possibility of biliary cancer and indicated that the stenotic legion was of submucosal, not mucosal, origin. Laparoscopic observations showed discoloration with wide yellowish-white lobular markings and wide depressed lesions at segments 2 and 7. Liver histology showed mild cholangitis with infiltration of IgG4-positive plasma cells around the bile ducts. Serum IgG4 levels were elevated. From these findings, the patient was diagnosed with IgG4-related sclerosing cholangitis. After treatment with prednisolone, blood liver enzymes and IgG4 rapidly normalized, bile duct dilatations improved, and the hepatic pseudotumor disappeared. The cholangitis did not recur. In this case, biliary cancer was ruled out by observation with peroral cholangioscopy, and the spread of cholangitis in the liver periphery was verified with laparoscopy; this information could not be obtained with other modalities.

Distinct histopathological features of Hashimoto's thyroiditis with respect to IgG4-related disease

A form of Hashimoto's thyroiditis with lymphoplasmacytic sclerosing changes and increased numbers of IgG4-positive plasma cells has recently been reported in the literature. These histopathological features suggest that this subtype of Hashimoto's thyroiditis may be closely related to IgG4-related disease. Therefore, this unique form of IgG4-related Hashimoto's thyroiditis, which is referred to as IgG4 thyroiditis, has its own clinical, serological, and sonographic features that are distinct from those associated with non-IgG4 thyroiditis. IgG4 thyroiditis shares similarities with the well-known fibrous variant of Hashimoto's thyroiditis; however, the detailed histopathological features of IgG4 thyroiditis have not been well established. Based on immunostaining results, 105 patients with Hashimoto's thyroiditis were divided into an IgG4 thyroiditis group (n=28) and a non-IgG4 thyroiditis group (n=77). As in our previous reports, IgG4 thyroiditis was associated with a patient population of a younger age, a lower female-to-male ratio, rapid progression, higher levels of thyroid autoantibodies, subclinical hypothyroidism, and diffuse sonographic echogenicity. Histopathologically, this group revealed severe lymphoplasmacytic infiltration, dense stromal fibrosis, marked follicular cell degeneration, numerous micro-follicles, and notable giant cell/histiocyte infiltration. Importantly, the IgG4-related group did not completely overlap with fibrous variant of Hashimoto's thyroiditis. Four cases (14%) in the IgG4 thyroiditis group presented only mild fibrosis in the stroma, whereas 29 cases (38%) in the non-IgG4 thyroiditis group met the diagnostic criteria for fibrous variant of Hashimoto's thyroiditis. Furthermore, we observed three patterns of stromal fibrosis in Hashimoto's thyroiditis: interfollicular fibrosis, interlobular fibrosis, and scar fibrosis. The IgG4 thyroiditis group was significantly associated with the presence of predominant interfollicular fibrosis. In conclusion, IgG4 Hashimoto's thyroiditis presents histopathological features quite distinct from its non-IgG4 counterpart.

Establishment of a standardized liver fibrosis model with different pathological stages in rats

Objective. To establish a standardized animal model for liver fibrosis with the same assessment criteria for liver fibrosis studies that have been established on a unified platform. Methods. The standardized liver fibrosis model was established using Sprague-Dawley (SD) rats that either received an intraperitoneal injection of carbon tetrachloride (CCl(4)) in small dosages or ingested an ethanol solution. Results. The definite corresponding rules among modeling of different weeks and corresponding serology indices as well as different pathological staging can be observed by modeling with small dosages and slow, individualized, and combined administrations. Conclusion. This method can be used for the standardized establishment of a liver fibrosis model in rats across 5 pathological stages, ranging from S0 to S4, with a high success rate (89.33%) and low death rate (17.3%) because of the application of multiple hypotoxic chemicals for modeling. We refer to the criteria of Histological Grading and Staging of Chronic Hepatitis for Fibrosis established by the 10th World Digestive Disease Academic Conference in Los Angeles in September 1994 (revised in November 2000).

Are Classification Criteria for IgG4-RD Now Possible? The Concept of IgG4-Related Disease and Proposal of Comprehensive Diagnostic Criteria in Japan

Recent studies suggest simultaneous or metachronous lesions in multiorgans characterized by elevated serum levels of IgG4 and abundant infiltration of IgG4-positive plasma cells with various degrees of fibrosis. Two Japanese research committees for IgG4-RD, one from fibrosclerosis (Okazaki team) and the other from lymph proliferation (Umehara team) supported by the “Research Program for Intractable Disease” of the Ministry of Health, Labor, and Welfare of Japan, have agreed with the unified nomenclature as “IgG4-RD” and proposed the comprehensive diagnostic criteria (CDC) for IgG4-RD. Validation of the CDC demonstrated satisfactory sensitivity for the practical use of general physicians and nonspecialists but low sensitivity in the organs to be difficult in taking biopsy specimens such as type1 autoimmune pancreatitis (IgG4-related AIP), compared with IgG4-related sialadenitis/dacryoadenitis (Mikulicz's disease) and IgG4-related kidney disease. Although the diagnostic criteria covering all IgG4-RD are hard to be established, combination with the CDC and organ-specific diagnostic criteria should improve sensitivity.

Spectrum of Disorders Associated with Elevated Serum IgG4 Levels Encountered in Clinical Practice

IgG4-related disease (IgG4-RD) is a recently described systemic fibroinflammatory disease associated with elevated circulating levels of IgG4 and manifests a wide spectrum of clinical presentations. Although serum IgG4 level has been described to be the most sensitive and specific laboratory test for the diagnosis of IgG4-RD, it is recognized that an elevated serum IgG4 level can be encountered in other diseases. In this study, we sought to identify the frequency of IgG4-RD and other disease associations in patients with elevated serum IgG4 levels seen in clinical practice. Among 3,300 patients who underwent IgG subclass testing over a 2-year period from January 2009 to December 2010, 158 (4.8%) had an elevated serum IgG4 level (>140 mg/dL). IgG4 subclass testing was performed for evaluation of suspected IgG4-RD or immunodeficiency. Twenty-nine patients (18.4%) had definite or possible IgG4-RD. Among those patients without IgG4-RD, a broad spectrum of biliary tract, pancreatic, liver, and lung diseases, as well as systemic vasculitis, was diagnosed. We conclude that patients with elevated serum IgG4 levels encountered in clinical practice manifest a wide array of disorders, and only a small minority of them has IgG4-RD.

Approach to a patient with elevated serum alkaline phosphatase

Cholestasis develops either from a defect in bile synthesis, impairment in bile secretion, or obstruction to bile flow, and is characterized by an elevated serum alkaline phosphatase and gamma-glutamyltransferase disproportionate to elevation of aminotransferase enzymes. Key elements to the diagnostic workup include visualization of the biliary tree by cholangiography and evaluation of liver histology. The hope is that recent advances in understanding the genetic factors and immune mechanisms involved in the pathogenesis of cholestasis will lead to newer therapeutic interventions in the treatment of these diseases.

Etiological factors in primary hepatic B-cell lymphoma

Sixty-four cases of malignant lymphoma involving the liver were examined. Of these, 20 cases were histologically confirmed to be primary hepatic B-cell lymphoma. Twelve of these 20 cases were diffuse large B-cell lymphoma (DLBCL) and eight cases were mucosa-associated lymphoid tissue (MALT) lymphoma. Of the 12 cases of DLBCL, six were immunohistologically positive for CD10 and/or Bcl6 (indicating a germinal center phenotype), six were positive for Bcl2, and five were positive for CD25. Eight of the 12 DLBCL cases (66.7%) and two of the eight MALT lymphoma cases (25%) had serum anti-hepatitis C virus (HCV) antibodies and HCV RNA. The incidence of HCV infection was significantly higher in the hepatic DLBCL cases than in systemic intravascular large B-cell cases with liver involvement (one of 11 cases, 9.1%) and T/NK-cell lymphoma cases (one of 19 cases, 5.3%) (p < 0.01 for both). Two hepatic DLBCL cases (16.7%) had rheumatoid arthritis treated with methotrexate, and four MALT lymphoma cases (50%) had Sjögren’s syndrome, primary biliary cirrhosis, or autoimmune hepatitis; one case in each of these two groups was complicated by chronic HCV-seropositive hepatitis. Although primary hepatic lymphoma is rare, persistent inflammatory processes associated with HCV infection or autoimmune disease may play independent roles in the lymphomagenesis of hepatic B cells.

IgG4-related sclerosing mesenteritis: a rare mesenteric disease of unknown etiology

Sclerosing mesenteritis is a rare inflammatory and fibrosing disorder of unknown etiology, while IgG4-related disease (IgG4-RD) consists of mass-forming, fibroinflammatory lesions characterized by high serum IgG4 levels and tissue infiltration of many IgG4-positive plasma cells; obliterative phlebitis is common. This report describes a case of sclerosing mesenteritis that was considered a manifestation of IgG4-RD. A 53-year-old man underwent right hemicolectomy because of an ileocecal mass that did not improve with conservative therapy. The ill-defined fibroinflammatory lesion extended in the mesentery with storiform fibrosis, obliterative phlebitis, and infiltration of many IgG4-positive plasma cells. The ratio of IgG4-positive/IgG-positive cells was 64%, and the ratio of forkhead box protein 3 (FOXP3)-positive/CD4-positive cells was elevated (13%). It is likely that at least some cases of sclerosing mesenteritis are a manifestation of IgG4-RD. It is important to investigate this relationship because steroid therapy may benefit such cases.

The Clinical and Pathological Features of IgG(4)-Related Disease

The rapidly emerging disorder now known as IgG(4)-related disease (IgG(4)-RD) includes a variety of clinical entities once regarded as being entirely separate diseases. Manifestations of IgG(4)-RD have now been reported in essentially all organ systems. Regardless of which organ is involved, tissue biopsies reveal striking histopathological similarities. The hallmark pathology findings are diffuse lymphoplasmacytic infiltrates, abundant IgG(4)-positive plasma cells, modest tissue eosinophilia, and extensive fibrosis. Tumorous swelling and obliterative phlebitis are other frequently observed features. Polyclonal elevations of serum IgG(4) are found in approximately 70% of patients. Many questions pertaining to the etiology, pathophysiology, epidemiology, clinical features, therapy, disease monitoring, and long-term outcomes remain to be addressed. This paper focuses on the clinical and pathological features of IgG(4)-RD.

Systemic immunoglobulin G4 (IgG4) disease and idiopathic orbital inflammation; removing 'idiopathic' from the nomenclature?

The discovery of systemic disease related to raised tissue and serum immunoglobulin G4 (IgG4) is changing diagnostic and therapeutic practice in many medical specialties. Orbital inflammation remains a diverse and heterogeneous group of disorders that can pose a diagnostic and therapeutic challenge, but with improved understanding and corresponding diagnostic advances the previously expansive group of idiopathies is reducing. The recent discovery that IgG4 has a causative role in a subtype of, what is currently termed, idiopathic orbital inflammation is encouraging. The term 'idiopathic' can now be removed from the nomenclature for another subtype of orbital inflammation. IgG4 disease should be especially considered in patients with a bilateral dacryoadenitis and systemic features (eg, lung and gastrointestinal involvement). However, reports are emerging suggesting that IgG4 may be responsible for more diverse disease subtypes. The relationship between IgG4-related disease and lymphoma remains unknown but vigilance is required.

Urologic manifestations of inflammatory pseudotumor: Report of 2 cases and review of the literature

We report two adult patients with varied urologic symptoms who were found to have inflammatory pseudotumor on histopathology. The first patient had a large, solid, enhancing retroperitoneal mass lesion and presented with increased frequency of urination and recurrent urinary tract infections. The second patient had an obstructing left distal ureteric stricture and presented with painless hematuria. Though preoperative radiological diagnosis of this entity is not feasible, the present article illustrates the imaging findings in this unusual disease entity with review of the relevant literature.

IgG4 Cholangiopathy

IgG4 cholangiopathy can involve any level of the biliary tree which exhibits sclerosing cholangitis or pseudotumorous hilar lesions. Most cases are associated with autoimmune pancreatitis, an important diagnostic clue. Without autoimmune pancreatitis, however, the diagnosis of IgG4-cholangiopathy is challenging. Indeed such cases have been treated surgically. IgG4-cholangiopathy should be diagnosed based on serological examinations including serum IgG4 concentrations, radiological features, and histological evidence of IgG4(+) plasma cell infiltration. Steroid therapy is very effective even at disease relapse. A Th2-dominant immune response or the activation of regulatory T cells seems to be involved in the underlying immune reaction. It is still unknown why IgG4 levels are specifically elevated in patients with this disease. IgG4 might be secondarily overexpressed by Th2 or regulatory cytokines given the lack of evidence that IgG4 is an autoantibody.

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

Immunoglobulin G4-related systemic disease (IgG4-RSD) is a recently defined emerging entity characterized by a diffuse or mass forming inflammatory reaction rich in IgG4-positive plasma cells associated with fibrosclerosis and obliterative phlebitis. IgG4-RSD usually affects middle aged and elderly patients, with a male predominance. It is associated with an elevated serum titer of IgG4, which acts as a marker for this recently characterized entity. The prototype is IgG4-related sclerosing pancreatitis or autoimmune pancreatitis (AIP). Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, however practically any organ can be involved, including upper aerodigestive tract, lung, aorta, mediastinum, retroperitoneum, soft tissue, skin, central nervous system, breast, kidney, and prostate. Fever or constitutional symptoms usually do not comprise part of the clinical picture. Laboratory findings detected include raised serum globulin, IgG and IgG4. An association with autoantibody detection (such as antinuclear antibodies and rheumatoid factor) is seen in some cases. Steroid therapy comprises the mainstay of treatment. Disease progression with involvement of multiple organ-sites may be encountered in a subset of cases and may follow a relapsing-remitting course. The principal histopathologic findings in several extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, along with atrophy and destruction of tissues. Immunohistochemical staining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). IgG4-RSD may potentially be rarely associated with the development of lymphoma and carcinoma. However, the nature and pathogenesis of IgG4-RSD are yet to be fully elucidated and provide immense scope for further studies.

Multifocal fibrosclerosis and IgG4-related disease involving the cardiovascular system

The cardiovascular system may be involved as a target organ of multifocal fibrosclerosis, which may manifest as idiopathic retroperitoneal fibrosis, inflammatory aortic aneurysm, inflammatory periarteritis, and inflammatory pericarditis. These pathological conditions can sometimes occur concomitantly. Idiopathic retroperitoneal fibrosis and inflammatory abdominal aortic aneurysm are both characterized by the presence of fibro-inflammatory tissue around the abdominal aorta expanding into the surrounding retroperitoneal structures, and together they may be termed 'chronic periaortitis'. Cardiovascular fibrosclerosis has become non-uncommonly encountered condition since imaging modalities have made its diagnosis more feasible. In addition, recent studies have demonstrated that a certain fraction, but not all, of cardiovascular fibrosclerosis may have a link with immunoglobulin-G4 (IgG4)-related sclerosing disease (IgG4-SD). IgG4-SD is histologically characterized by dense fibrosclerosis and infiltration of lymphocytes and IgG4-positive plasma cells, and these histopathologic findings seem to be essentially similar regardless of the organs involved. In this mini review, we summarize what is known so far about multifocal fibrosclerosis of the cardiovascular system and its association with IgG4-SD, and what remains to be clarified in future investigations.

Autoimmune pancreatitis versus pancreatic cancer: a comprehensive review with emphasis on differential diagnosis

BACKGROUND

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis with a discrete pathophysiology, occasional diagnostic radiological findings, and characteristic histological features. Its etiology and pathogenesis are still under investigation, especially during the last decade. Another aspect of interest is the attempt to establish specific criteria for the differential diagnosis between autoimmune pancreatitis and pancreatic cancer, entities that are frequently indistinguishable.

DATA SOURCES

An extensive search of the PubMed database was performed with emphasis on articles about the differential diagnosis between autoimmune pancreatitis and pancreatic cancer up to the present.

RESULTS

The most interesting outcome of recent research is the theory that autoimmune pancreatitis and its various extra-pancreatic manifestations represent a systemic fibro-inflammatory process called IgG4-related systemic disease. The diagnostic criteria proposed by the Japanese Pancreatic Society, the more expanded HISORt criteria, the new definitions of histological types, and the new guidelines of the International Association of Pancreatology help to establish the diagnosis of the disease types.

CONCLUSION

The valuable help of the proposed criteria for the differential diagnosis between autoimmune pancreatitis and pancreatic cancer may lead to avoidance of pointless surgical treatments and increased patient morbidity.

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.

Infraorbital nerve swelling associated with autoimmune pancreatitis

PURPOSE

The aim of our study was to examine the relation between autoimmune pancreatitis (AIP) and infraorbital nerve swelling.

MATERIALS AND METHODS

A total of 11 AIP patients underwent magnetic resonance imaging (MRI) examination of the head and neck region. The infraorbital nerve thicknesses were measured on coronal images and compared with those of a control group. We also examined whether the infraorbital nerve thicknesses were altered from before to after steroid therapy in nine patients who underwent MRI examination after such therapy.

RESULTS

The mean thicknesses were 3.8 ± 2.0 mm in the AIP group and 2.6 ± 0.5 mm in the control group (P < 0.05). The nerve thicknesses were >5 mm in 5 of 11 patients (45%) in the AIP group, and <5 mm in all of the control group. Among the nine patients who underwent MRI examination after steroid therapy, three had shown nerve swelling before steroid therapy; the therapy diminished the swelling in all three patients.

CONCLUSION

Infraorbital nerve swelling was observed more frequently in AIP patients than in patients without a history of AIP. Therefore, such swelling seems to be an extrapancreatic lesion of AIP.

Pathological features of IgG4-related sclerosing disease

PURPOSE OF REVIEW

The spectrum of IgG4-related systemic disease (IgG4-RSD) continues to widen. At most of the sites involved by this condition, the clinical presentation can mimic neoplasm. Pathologic assessment of small biopsies can be critical to proper management. This review summarizes the histologic features of IgG4-RSD and the role of immunohistochemistry of IgG4 in the diagnosis.

RECENT FINDINGS

The review period saw further expansion of the list of sites putatively involved by IgG4-RSD, with new, or more detailed, entries related to lung, lymph nodes, stomach, and thyroid. A tentative consensus was reached on the issue of subtypes of autoimmune pancreatitis. The role of immunohistochemistry for IgG4 as an adjunct to the diagnosis of IgG4-RSD was further clarified.

SUMMARY

Sclerosing lymphoplasmacytic inflammation at almost any site can represent a manifestation of IgG4-RSD. There are several histologic features that can suggest the diagnosis. Immunohistochemistry for IgG4 is a useful diagnostic test to further support the diagnosis.

Immunoglobulin G4 (IgG4)-positive or -negative ocular adnexal benign lymphoid lesions in relation to systemic involvement

The purpose of this study is to determine the relationship of ocular adnexal benign or reactive lymphoid hyperplasia, including orbital pseudotumor, with immunoglobulin G4 (IgG4)-related diseases. Medical charts of 9 consecutive patients with ocular adnexal benign lymphoid lesions, seen in the Department of Ophthalmology, Okayama University Hospital, were reviewed, and pathological sections were restained immunohistochemically for IgG4-, IgG-, and CD138-positive plasma cells. The diagnosis of IgG4-positive lesions was based on 10 or more IgG4-positive plasma cells in a high-power field and greater than 40% ratios of IgG4-positive plasma cells/CD138-positive plasma cells and IgG4-positive plasma cells/IgG-positive plasma cells. IgG4-positive lesions were determined as absent in 5 patients (4 with bilateral lacrimal/orbital lesions and one with a unilateral conjunctival lesion), none of whom showed systemic manifestations. In contrast, IgG4-positive lesions were present in 4 patients (3 with bilateral lacrimal/orbital lesions and one with a unilateral lacrimal/orbital lesion), who showed systemic manifestations : one with Hashimoto thyroiditis, one with IgG4-positive bilateral interstitial lung disease and hepatic inflammatory pseudotumor, one with bilateral interstitial lung disease, and one with systemic lymphadenopathy and antiphospholipid syndrome. In conclusion, IgG4-positive ocular adnexal benign lymphoid lesions might be used as a benchmark for the probable presence of other systemic lymphoid lesions.

Marginal zone lymphomas involving meningeal dura: possible link to IgG4-related diseases

Dura-based marginal zone lymphomas represent an uncommon group of low-grade B-cell neoplasms, and literature regarding the clinical, histological and genetic profile of these tumors in the context of the newly described IgG4-related entities is lacking. We analyzed 32 dura-based marginal zone lymphomas identified in 27 females and 5 males ranging in age from 33-82 years (median 50). Morphologic examination, immunohistochemical studies and PCR for B-cell clonality were carried out in all cases. In addition, IgG4 immunohistochemistry and cytogenetic studies (either by FISH or RT-PCR) were carried out in 20 (18 primary dural; 2 with associated extradural disease) and 9 cases, respectively. Clinically, most cases presented radiologically as dura-based masses, mimicking meningioma. Histologically, the majority exhibited plasmacytoid differentiation, and were clonal either by PCR or immunohistochemical light chain analysis (28 out of 32). In the subset tested for IgG4, 6 of 18 primary dural marginal zone lymphoma (including one epidural tumor) showed numerous IgG4-positive plasma cells; all 6 were light chain restricted and clonal by PCR in 5 of 6 tested cases. Three IgG4-positive marginal zone lymphomas tested for cytogenetics did not show any cytogenetic aberrations. Across all cases, FISH and RT-PCR identified abnormalities in three out of nine cases (trisomies 3 and 18; trisomies 3 and 1; trisomy 18) without any extranodal marginal zone lymphoma specific translocations. Regardless of the treatment modality, 16 of 17 patients with follow-up are alive without evidence of disease over a period of 4-124 months (median 19.5). The expression of IgG4 in light-chain-restricted clonal plasma cells of a significant subset of dural marginal zone lymphomas, including one in an epidural location, is a novel finding and points to distinctive biology. Cytogenetic aberrations are present only in a minority of dural marginal zone lymphomas.

IgG4-associated inflammatory pseudotumor of ureter: clinicopathologic and immunohistochemical study of 3 cases

Inflammatory pseudotumors are lesions characterized by proliferation of fibroblasts/myofibroblasts with variable chronic inflammatory cell infiltration. Recent studies have suggested that inflammatory pseudotumor with abundant IgG4-positive plasma cells may be a unique entity associated with systemic IgG4-related sclerosing disease and should be distinguished from other similar lesions such as inflammatory myofibroblastic tumor and fibrohistiocytic-type inflammatory pseudotumor. Localized inflammatory pseudotumor has been rarely reported in the ureter, and IgG4-associated inflammatory pseudotumor of ureter has not been described. We describe herein 3 cases of ureteral inflammatory pseudotumor of IgG4-associated lymphoplasmacytic type, focusing on density of IgG4-positive plasma cells; infiltration pattern of eosinophils and histiocytes; presence of obliterative phlebitis; and immunohistochemical profiles of smooth muscle actin, anaplastic lymphoma kinase, and CD68. Three patients, 45- and 47-year-old men and 84-year-old woman, all presented with flank pain and ureteral narrowing by a mass effect. Microscopic examination of the resected ureters showed suburothelial masslike lesions with fibroblasts/myofibroblasts without atypia, abundant plasma cells, and scattered eosinophils and histiocytes. The lesion of the 47-year-old man showed obliterative phlebitis in addition to the above findings. The lesion of the 84-year-old woman was accompanied by urothelial carcinoma in situ in the overlying urothelium. Spindle cells were diffusely or focally positive for smooth muscle actin but negative for anaplastic lymphoma kinase in all 3 cases. For each case, respectively, an average of 154, 112, and 50 plasma cells per high-power fields were immunoreactive for IgG4, a diagnostic feature of IgG4 inflammatory pseudotumor. We described 3 cases of IgG4-associated inflammatory pseudotumor of ureter with pathologic and immunohistochemical features that are compatible for lymphoplasmacytic type of inflammatory pseudotumor. Further study is needed to characterize any relationship between this entity and systemic sclerosing disease and/or urothelial carcinogenesis.

Orbital necrobiotic xanthogranuloma associated with systemic IgG4 disease

PURPOSE

The authors describe 2 cases of orbital xanthogranulomatous disease associated with an increase in IgG4-positive plasma cells, and also examine IgG4 in other types of orbital inflammation.

METHODS

Immunohistochemistry for total IgG and IgG4 was performed in 18 cases of orbital inflammation, including chronic dacryoadenitis (n=10), necrobiotic xanthogranuloma (n=2), xanthogranuloma (n=1), idiopathic orbital inflammation/pseudotumor (n=4), and fungal infection (n=1).

RESULTS

One patient presenting with necrobiotic xanthogranuloma had signs of systemic IgG4 disease. His orbital lesion showed an elevated number of IgG4 positive plasma cells (55%). An orbital xanthogranulomatous lesion in a second patient lacking systemic symptoms also contained a high percentage of IgG4-positive plasma cells (80%). Only 1 case of chronic dacryoadenitis contained prominent IgG4-positive plasma cells (mean 17/hpf).

CONCLUSIONS

IgG4-positive plasma cells are relatively rare in nonsclerosing orbital inflammatory lesions. However, systemic disease IgG4 can be associated with necrobiotic xanthogranuloma of the orbit.

IgG4-related meningeal disease: clinico-pathological features and proposal for diagnostic criteria

IgG4-related disease has evolved from originally being recognized as a form of pancreatitis to encompass diseases of numerous organs including the hypophysis and one reported case of dural involvement. A search of the University of Virginia, Division of Neuropathology files for 10 years identified ten cases of unexplained lymphoplasmacytic meningeal inflammation that we then evaluated using immunohistochemical stains for IgG4 and IgG. Ten control cases including sarcoidosis (4), tuberculosis (1), bacterial abscess (2), Langerhans cell histiocytosis (2), and foreign body reaction (1) were also examined. The number of IgG4-positive plasma cells was counted in five high power fields (HPFs) and an average per HPF was calculated. Cases that contained greater than ten IgG4-positive cells/HPF were considered to be IgG4-related. Five of the study cases met these criteria, including one case of leptomeningeal inflammation. All cases exhibited the typical histological features of IgG4-related disease including lymphoplasmacytic inflammation, fibrosis, and phlebitis. The dural-based lesions appear to represent a subset of the cases historically diagnosed as idiopathic hypertrophic pachymeningitis. While the leptomeningeal process most closely resembles non-vasculitic autoimmune inflammatory meningoencephalitis. Given these findings, IgG4-related meningitis should be considered in the differential diagnosis of meningeal inflammatory lesions after stringent clinical and histologic criteria are used to rule out other possible diagnoses.

IgG4-related inflammatory pseudotumor of the trigeminal nerve: another component of IgG4-related sclerosing disease?

IgG4-related IPTs have been reported in various sites and may form part of the spectrum of systemic IgG4-related sclerosing disease. Some pseudotumors are clinically and radiologically indistinguishable from malignant tumors. We present the first case of an IgG4-related IPT of the trigeminal nerve diagnosed histopathologically without involvement of any of the common sites. The trigeminal nerve pseudotumor may represent a component of IgG4-related sclerosing disease.

Chronic gastritis in the setting of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a recently recognized disease entity. In some patients, this disease is associated with other inflammatory diseases. In this study, we aimed to elucidate the pathologic characteristics of AIP-associated gastritis (AIP-G). We evaluated and compared the pathologic findings and immunohistochemical expressions of immunoglobulin G (IgG)4 and IgG in gastric biopsy specimens from 13 AIP-G patients with those from patients of 2 control groups. We divided the AIP-G patients who did not receive steroid therapy [AIP-G-ST(-)] into the following 2 groups: without Helicobacter pylori (HP) infection [AIP-G-HP(-)] and with HP infection [AIP-G-HP(+)]. The control groups comprised 19 patients who were diagnosed with chronic active gastritis associated with HP infection and 7 patients with nonsteroidal anti-inflammatory drug-induced gastritis. We classified the findings for the gastric mucosa into those for the upper and the lower lamina propria. The characteristic finding of AIP-G groups was diffusely lymphoplasmacytic infiltration in the lamina propria. The IgG4-positive plasma cell/IgG-positive plasma cell ratios (IgG4/IgG ratios) in both the upper and lower lamina propria in the AIP-G-ST(-) groups were predominantly higher than the corresponding values in the other groups. In the AIP-G-ST(-) groups, the IgG4/IgG ratio in the lower lamina propria was predominantly higher than that in the upper lamina propria, irrespective of the HP status. In conclusion, diffuse lymphoplasmacytic infiltration in the lamina propria and increased IgG4/IgG ratio in the gastric mucosa (notably in the lower lamina propria) may be the characteristic findings of AIP-G.