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

Immunoglobulin G4-Related Disease: An Update

Immunoglobulin G4-related disease (IgG4-RD) is an increasingly recognized immune-mediated condition comprised of a collection of disorders that share specific pathological, serological, and clinical features. IgG4-RD is a fibroinflammatory condition with a tendency to form tumors with inflammatory infiltrate with IgG4 rich plasma cells and elevation of serum IgG4, which may affect virtually every organ and tissue. IgG4-related ophthalmic disease may present as dacryoadenitis, myositis, or involvement of other orbital tissue. Hypophysitis or pachymeningitis may manifest as cranial neuropathies. The diagnosis of IgG4-RD is based on a typical clinical scenario, supportive laboratory test, expected radiological characteristics, and distinct histopathological and immunohistochemical features. Corticosteroids and immunosuppressives form the mainline treatment.

Localized intrahepatic IgG4-related sclerosing cholangitis (IgG4-SC) as an additional type of IgG4-SC: a systematic analysis of 12 cases

OBJECTIVES

IgG4-related sclerosing cholangitis (IgG4-SC), a recently defined disease entity, has been classified into four types based on the stricture regions revealed by cholangiography. However, localized intrahepatic IgG4-SC is not included into the classification. This study aimed to analyze and characterize localized intrahepatic IgG4-SC and justify the inclusion of this type into the classification.

METHODS

PubMed and Embase were searched for studies published from March 2001 to June 2017 reporting localized intrahepatic IgG4-SC. Data were obtained and analyzed from the included articles.

RESULTS

Twelve cases of localized intrahepatic IgG4-SC were included. All patients were adults with the median age of 73 years (range 46-78), and had a male preponderance (88.9%). The most common clinical presentation was obstructive jaundice (50%), abdominal pain (25%) and absence of symptoms (25%). On imaging and macroscopically, localized intrahepatic IgG4-SC presented with three subtypes, i.e., mass-forming (n = 6, 50%), stricture (n = 5, 41.7%) and periductal infiltrating (n = 1, 8.3%) subtypes. Among the eight cases with diagnoses reported, six patients were misdiagnosed as intrahepatic cholangiocarcinoma; one was diagnosed as hepatic mass and one as IgG4-SC before biopsy or operation. Information on treatment was available on 10 cases; eight underwent surgical resection, one received steroid treatment alone and one underwent endoscopic biliary drainage. No relapse was noted in patients with surgical resection during a period of followed up.

CONCLUSIONS

The localized intrahepatic IgG4-SC presents with mass-forming, stricture and periductal infiltrating subtypes, and should be recognized as an additional type of IgG4-SC according to the cholangiographic classification or anatomic site.

Case report: IgG4-related mass-forming thyroiditis accompanied by regional lymphadenopathy

Background

It has been recently accepted that IgG4-related thyroiditis is comparable to the Hashimoto and Riedel thyroiditis and Graves disease which are rich in IgG4-secreting plasma cells. Many physicians believe that in IgG4-related thyroiditis, the thyroid is entirely enlarged and diffusely affected, which is similar to conventional thyroiditis, but rarely ever accompanied by pseudoneoplastic mass formation as in IgG4-related disease in the other organs. This report introduces another pattern of IgG4-related thyroiditis as mass-forming thyroiditis and presents the occurrence of IgG4-related regional lymphadenopathy as an unusual accompanying symptom.

Case presentation

A 66-year-old woman presented with an approximately 2.5-cm mass in the right thyroidal lobe and regional lymph node swelling, which were preoperatively misinterpreted as thyroidal carcinoma. After lobectomy, histological examination was performed, revealing that the mass showed dense stromal fibrosis, lymphoplasmacytic infiltration, and effacement of thyroid follicles, while the background thyroidal tissue seemed to mimic lymphocytic thyroiditis without fibrosis. Immunohistochemistry revealed predominance of IgG4-secreting plasma cells among infiltrating lymphocytes independent of mass lesion or background tissue. In addition, the regional Delphian and paratracheal lymph nodes were swollen, histologically showing numerous IgG4-secreting plasma cell infiltrations in the interfollicular zone.

Conclusions

IgG4-related mass-forming thyroiditis, which may be an extremely rare but recognizable pattern of IgG4-related thyroiditis, may be distinguishable from Hashimoto and Riedel thyroiditis, Graves disease, and thyroidal carcinoma. In addition, the regional IgG4-related lymphadenopathy, also possibly misdiagnosed as metastatic thyroidal carcinoma, may be a newly recognized manifestation of IgG4-related thyroiditis.

Role of MR in the differentiation of IgG4-related from non-IgG4-related hepatic inflammatory pseudotumor

BACKGROUND

Hepatic inflammatory pseudotumor (IPT) is classified into 2 types based on IgG4 stain: IgG4-related and non-IgG4-related; the two types differ not only in their pathological characteristics, but also in the clinical features. This study aimed to investigate the MR character of hepatic IPT, and differentiate the IgG4-related IPT from the non-IgG4-related IPT.

METHODS

Twenty-five patients with 27 histologically proven hepatic IPTs were retrospectively analyzed. Ten lesions were diagnosed as IgG4-related IPT, and the other 17 as non-IgG4-related IPT. The MR signal features on T1, T2-weighted, dynamic-enhanced, and diffusion-weighted imaging were evaluated and compared.

RESULTS

The dominant lesions were subcapsularly distributed (n=17, 63.0%) with clear boundary (n=20, 74.1%), and showed progressive enhancement pattern (n=21, 77.8%) with diffuse homogeneous (n=12, 44.4%) or heterogeneous (n=8, 29.6%) hyperintensity, accompanied by delayed capsule-like enhancement (n=17, 63.0%) and central nonenhanced areas (n=18, 66.7%). Morphological features (P>0.05) were not sufficient to differentiate IgG4-related IPT from non-IgG4-related IPT; the wash-out pattern was only found in 2 IgG4-related IPT, while the progressive enhancement pattern was more common in the non-IgG4-related lesions (n=16) (P=0.022). During portal and delayed phases, iso-/hypoenhanced lesions were only seen in 3 IgG4-related IPT, and circular-enhanced lesions (n=5) existed exceptionally in the non-IgG4-related group with significant differences (P=0.029 and 0.027). Most IgG4-related IPTs had lower apparent diffusion coefficient compared with the liver parenchyma (n=6), while most non-IgG4-related IPTs had higher apparent diffusion coefficient value (n=13) (P=0.046).

CONCLUSIONS

Although MR images of hepatic IPT have certain characteristics, they are not enough to differentiate IgG4-related IPT from non-IgG4-related IPT. The enhancement pattern, signal features on portal and delayed phases, and the apparent diffusion coefficient value of the lesion may be helpful for the diagnosis.

IgG4-related disease: with emphasis on the biopsy diagnosis of autoimmune pancreatitis and sclerosing cholangitis

In 2011, chronic fibroinflammatory processes occurring simultaneously or metachronously in various organs and associated with elevated IgG4 serum levels and/or tissue infiltration with IgG4-positive plasma cells have been recognized as manifestations of a systemic disorder called IgG4-related disease (IgG4-RD). The histologic key findings are lymphoplasmacytic infiltration rich in IgG4-positive plasma cells combined with storiform fibrosis and obliterative phlebitis. Among the organs mainly affected by IgG4-RD are the pancreas and the extrahepatic bile ducts. The pancreatic and biliary alterations have been described under the terms autoimmune pancreatitis (AIP) and sclerosing cholangitis, respectively. These diseases are currently more precisely called IgG4-related pancreatitis (or type 1 AIP to distinguish it from type 2 AIP that is unrelated to IgG4-RD) and IgG4-related sclerosing cholangitis (IgG4-related SC). Clinically and grossly, both diseases commonly imitate pancreatic and biliary adenocarcinoma, tumors that are well known for their dismal prognosis. As IgG4-RD responds to steroid treatment, making a resection of a suspected tumor unnecessary, a biopsy is often required to establish the preoperative diagnosis. This review discusses the morphologic spectrum of IgG4-related pancreatitis and IgG4-related SC and focuses on the biopsy relevant histologic features for the diagnosis and differential diagnosis of these diseases.

[Hepatopancreaticobiliary diseases in IgG4-associated autoimmune diseases]

BACKGROUND

IgG4-related diseases are rare systemic multiorgan diseases and can thus affect any organ system. The incidence of diagnosis has significantly increased due to increasing awareness.

OBJECTIVE

In the abdomen the hepatopancreaticobiliary system provides an essential organ system for the expression of IgG4-associated autoimmune diseases. The focus here is autoimmune pancreatitis type 1 but IgG4-associated sclerosing cholangitis and IgG4-associated hepatopathy, which can also occur in combination are less well-known.

METHODS

Various mostly Asiatic, histologically-based diagnostic systems, such as HISORt or international consensus diagnostic criteria (ICDC) are available for the diagnostics of hepatopancreaticobiliary IgG4-related autoimmune diseases, in which imaging techniques playing an increasingly important role.

RESULTS

In addition to generalized organ swelling further morphological and also functional imaging criteria have become increasingly well-known for autoimmune pancreatitis, such as late enhancement or the imaging response to steroid therapy. Magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERP) can provide valuable information for the diagnostics of IgG4-related diseases in the hepatopancreaticobiliary system.

CONCLUSION

IgG4-related autoimmune diseases of the hepatopancreaticobiliary system are a rare group of diseases in which increasing knowledge of the radiological appearance also leads to an increasingly frequency of diagnosis. IgG4-related diseases must be distinguished from non-necrotizing pancreatitis and pancreatic cancer, which is often difficult but has significant therapeutic consequences for the patients.

Expansion of blood IgG4+ B, TH2, and regulatory T cells in patients with IgG4-related disease

BACKGROUND

IgG₄-related disease (IgG₄-RD) is a systemic fibroinflammatory condition affecting various organs and has a diverse clinical presentation. Fibrosis and accumulation of IgG₄⁺ plasma cells in tissue are hallmarks of the disease, and IgG₄-RD is associated with increased IgG₄ serum levels. However, disease pathogenesis is still unclear, and these cellular and molecular parameters are neither sensitive nor specific for the diagnosis of IgG₄-RD.

OBJECTIVE

Here we sought to develop a flow cytometric gating strategy to reliably identify blood IgG₄⁺ B cells to study their cellular and molecular characteristics and investigate their contribution in disease pathogenesis.

METHODS

Sixteen patients with histologically confirmed IgG₄-RD, 11 patients with sarcoidosis, and 30 healthy subjects were included for 11-color flow cytometric analysis of peripheral blood for IgG₄-expressing B cells and T_H subsets. In addition, detailed analysis of activation markers and chemokine receptors was performed on IgG₄-expressing B cells, and IgG₄ transcripts were analyzed for somatic hypermutations.

RESULTS

Cellular and molecular analyses revealed increased numbers of blood IgG₄⁺ memory B cells in patients with IgG₄-RD. These cells showed reduced expression of CD27 and CXCR5 and increased signs of antibody maturation. Furthermore, patients with IgG₄-RD, but not patients with sarcoidosis, had increased numbers of circulating plasmablasts and CD21^low B cells, as well as T_H2 and regulatory T cells, indicating a common disease pathogenesis in patients with IgG₄-RD.

CONCLUSION

These results provide new insights into the dysregulated IgG₄ response in patients with IgG₄-RD. A specific "peripheral lymphocyte signature" observed in patients with IgG₄-RD, could support diagnosis and treatment monitoring.

IgG4-related Disease and the Liver

Pathologists are likely to encounter IgG4-related disease in several organ systems. This article focuses on helping pathologists diagnose IgG4-related disease in the hepatobiliary system. Missing the diagnosis can result in unnecessary organ damage and/or unnecessary surgical and cancer therapy. In the liver, tumefactive lesion(s) involving the bile ducts with storiform fibrosis and an IgG4-enriched lymphoplasmacytic infiltrate are highly concerning for IgG4-related disease. The recent identification of oligoclonal populations of T cells and B cells in IgG4-related disease may lead to molecular tests, new therapeutics, and a greater mechanistic understanding of the disease.

A Comparative Study of Inflammatory Myofibroblastic Tumors and Tumefactive IgG4-related Inflammatory Lesions: the Relevance of IgG4 Plasma Cells

IgG4-related disease is a recently recognized systemic condition characterized by tumefactive lesions at various sites. Inflammatory pseudotumor (IPT), a tumefactive mass lesion with an unknown etiology, belongs to the spectrum of IgG4-related disease. Inflammatory myofibroblastic tumor (IMT), previously considered under the umbrella of IPT, is now classified as a clonal neoplasm. Previously, both the terms were used interchangeably, because of overlapping morphologic features. This study was carried out to compare the morphologic and the immunohistochemical features of these entities and to study the role of IgG4 in their pathogenesis. Thirty-nine cases comprising of IMT (n=18) and IPT (n=21) were retrieved, and their clinical, morphologic, and immunohistochemical features were studied. IMT was more common in children as compared with IPT. IMT cases showed the proliferation of myofibroblastic cells accompanied by a variable inflammatory infiltrate, whereas IPT cases showed predominantly stromal fibrosis and a lymphoplasmacytic infiltrate with a subset of cases showing a storiform fibrosis and obliterative phlebitis. Anaplastic lymphoma kinase-1 (ALK-1) was positive in 12 of the 18 (66.7%) IMT cases, whereas none of the IPT cases showed ALK-1 immunoreactivity. IPT cases showed significantly increased IgG4+ plasma cells (mean, 127.8/high-power fields vs. 17.8/high-power fields) and a higher IgG4/IgG ratio (mean, 48.2% vs. 10.7%) as compared with IMT. Fluorescence in situ hybridization analysis was positive for ALK rearrangement in 6 of the 9 IMT cases tested. In conclusion, most of the IPT cases can be considered as IgG4 related on the basis of their histopathologic features and immunohistochemistry criteria. However, IMT represents a myofibroblastic neoplasm with ALK-1 overexpression and is clearly not IgG4 related.

A Solid Pseudopapillary Neoplasm of the Pancreas Associated With IgG4-Related Pancreatitis: A Case Report

A solid and cystic pancreatic lesion was incidentally found in a 62-year-old woman on abdominal computed tomography. The lesion was diagnosed as a solid pseudopapillary neoplasm by using endoscopic ultrasound-guided fine needle aspiration, and the tumor was resected. Histologically, the tumor cells had relatively small, round nuclei and papillary-like architecture in a hemorrhagic background. On immunohistochemical examination, the tumor cells were diffusely positive for nuclear β-catenin and cytoplasmic CD10. In addition, typical histological findings of IgG4-related pancreatitis (obstructive phlebitis, storiform-type fibrosis, and abundant IgG4-positive plasma cell infiltration) were found in the surrounding stroma of the solid pseudopapillary neoplasm. Postoperative workup failed to detect any other sclerotic lesions or serum IgG4 elevation, suggesting that the patient had no evidence of IgG4-related disease. To avoid misdiagnosis of a combined pancreatic neoplasm and fibro-inflammatory lesion, pathologists should consider such situations and make a definitive diagnosis after careful observation of all pancreatic lesions.

Pediatric cholangiopathies: diseases of the gallbladder and biliary tract

Pediatric gallbladder and bile duct disease encompasses a broad spectrum of processes, from congenital to developmental to neoplastic. We describe normal pediatric biliary anatomy and summarize the most common pathologic entities, with a focus on non-invasive imaging techniques and findings. Ultrasound is the first-line imaging modality in children with suspected biliary pathology based on its widespread availability, cost effectiveness, and lack of ionizing radiation. MRI and MRCP are often used for further evaluation in cases of diagnostic uncertainty and for surgical planning.

Biliary tumors with pancreatic counterparts

Some biliary diseases mimic pancreatic diseases pathologically as well as pathogenetically. Such diseases can be called "biliary diseases with pancreatic counterparts". Biliary intraepithelial neoplasm (BilIN), intraductal papillary neoplasm of bile ducts (IPNB), hepatobiliary mucinous cystic neoplasm (hMCN), and IgG4-inflammatory pseudotumor represent the biliary counterparts of pancreatic intraepithelial neoplasm (PanIN), intraductal papillary mucinous neoplasm of pancreas (IPMN), pancreatic MCN, and mass forming type 1 autoimmune pancreatitis (AIP), respectively. BilIN and PanIN represent pre-invasive intraepithelial stages of nodular sclerosing cholangiocarcinoma and pancreatic ductal adenocarcinoma, respectively. IPNB and IPMN are grossly visible, predominant papillary, intraductal neoplasms that may progress to invasive carcinoma. Morphologically similar MCNs with subepithelial ovarian-like stroma occur in both the hepatobiliary system as well as the pancreas. IgG4-inflammatory pseudotumor, usually of the lymphoplasmacytic type, and mass forming type 1 AIP represent IgG4-related disease in the biliary tree and pancreas respectively. The biliary tract, which is associated with the peribiliary glands, including the pancreatic acini, can be regarded as an incomplete pancreas, so several diseases mimicking pancreatic diseases may be expected to occur in the biliary tract (biliary diseases with pancreatic counterparts).

Immunoglobulin G4-related hepatic inflammatory pseudotumor invading the abdominal wall

A 50-year-old woman presented with epigastralgia. Computed tomography (CT) of the abdomen revealed a 6-cm well-enhanced mass extending from the left lobe of the liver to the abdominal wall, suggestive of cholangiocarcinoma. Liver and skin mass biopsies did not provide evidence of hepatic malignancy but were rich in plasma cells and sclerotic lesions. Subsequent detection of elevated serum immunoglobulin G4 (IgG4) led to a diagnosis IgG4-related inflammatory pseudotumor (IPT) of the liver. Treatment with systemic corticosteroids resulted in rapid clinical improvement. This case is the first report of an IgG4-related hepatic IPT invading the abdominal wall.

IgG4-related hepatobiliary disease: an overview

IgG4-related hepatobiliary diseases are part of a multiorgan fibroinflammatory condition termed IgG4-related disease, and include IgG4-related sclerosing cholangitis (IgG4-SC) and IgG4-related hepatopathy. These diseases can present with biliary strictures and/or mass lesions, making them difficult to differentiate from primary sclerosing cholangitis (PSC) or other hepatobiliary malignancies. Diagnosis is based on a combination of clinical, biochemical, radiological and histological findings. However, a gold standard diagnostic test is lacking, warranting the identification of more specific disease markers. Novel assays - such as the serum IgG4:IgG1 ratio and IgG4:IgG RNA ratio (which distinguish IgG4-SC from PSC with high serum IgG4 levels), and plasmablast expansion to recognize IgG4-SC with normal serum IgG4 levels - require further validation. Steroids and other immunosuppressive therapies can lead to clinical and radiological improvement when given in the inflammatory phase of the disease, but evidence for the efficacy of treatment regimens is limited. Progressive fibrosclerotic disease, liver cirrhosis and an increased risk of malignancy are now recognized outcomes. Insights into the genetic and immunological features of the disease have increased over the past decade, with an emphasis on HLAs, T cells, circulating memory B cells and plasmablasts, chemokine-mediated trafficking, as well as the role of the innate immune system.

IgG4-related inflammatory pseudotumor: A systematic review of histopathological features of reported cases

OBJECTIVES

There is marked inconsistency in reporting the key features of IgG4-related inflammatory pseudotumor (IPT) cases. We aimed to analyze the various aspects of IgG4-related IPTs and to test the performance of the consensus criteria for their diagnosis.

METHODS

PubMed database was searched for IgG4-related IPT cases. The data regarding patient demographics, clinical presentation, laboratory findings, histopathological features, and treatment response are extracted and are presented here in a descriptive manner.

RESULTS

The study included 40 papers describing the clinicopathological features of 83 IPTs in 80 patients. Seventeen cases were diagnosed on biopsies; while remaining were diagnosed on excision specimens. Among these, 50 cases were categorized as highly suggestive and 24 cases as probable for IgG4RD; while nine cases had insufficient histopathological evidence of IgG4RD. Two cases diagnosed on biopsies having insufficient evidence of IgG4RD showed partial or no response to steroids; while 12/14 cases (85.71%) diagnosed on biopsies that were histologically suggestive or probable for IgG4RD showed prompt response to steroids.

CONCLUSION

Many reports have not specifically mentioned the full histopathological findings of IgG4-related IPTs that may hinder in refining the diagnostic criteria of IgG4RD. The IgG4-related IPTs diagnosed on biopsies with requisite features showed prompt response to steroids indicating specificity of histopathological findings in predicting treatment response.

MRI characteristics for the differential diagnosis of benign and malignant small solitary hypovascular hepatic nodules

PURPOSE

To compare the MRI findings of benign and malignant solitary hypovascular hepatic nodules and identify the differentiating features.

MATERIALS AND METHODS

A total of 135 patients with solitary hypovascular hepatic lesions up to 3 cm (mass forming intrahepatic cholangiocarcinoma, n=29; metastases, n=26; inflammatory pseudotumors and solitary necrotic nodule, n=48; and hemangioma, n=32) were assessed. MRI findings were analyzed, and lesions were scored for peripheral and intratumoral appearance and enhancement patterns.

RESULTS

Univariate and multivariate analyses showed that the most common findings for benign lesions were subcapsular, sharp margin, homogeneous, marked high signal on T2WI, mild hyperintensity on T2WI, increasing intensity of peripheral globular enhancement, and persistent central septum-like linear enhancement on delayed phase (P<0.05). An area under the curve of 0.955 was obtained for differentiating malignant from benign nodules using the combined imaging features of ill-defined margins, heterogeneity, decreasing intensity of peripheral rim-like enhancement, and central increasing intensity of patchy enhancement. Interobserver agreement was good, ranging from 0.72 to 1.00.

CONCLUSION

MRI may be a useful noninvasive method for determining whether hypovascular hepatic nodules are malignant or benign.

IgG4-related sclerosing cholangitis: all we need to know

Our knowledge and experience of IgG4-related sclerosing cholangitis (ISC) have expanded in the last decade. ISC is one of the common organ manifestations of IgG4-related disease (IgG4-RD); approximately 60 % of patients with this systemic condition have ISC in the proximal and/or distal bile ducts. ISC needs to be discriminated from primary sclerosing cholangitis, cholangiocarcinoma, and other rare forms of lymphoplasmacytic cholangiopathy (e.g., follicular cholangitis and sclerosing cholangitis with granulocytic epithelial lesions). Its diagnosis requires a multidisciplinary approach, in which serology, histology, and imaging play crucial roles. Treatments with high-dose corticosteroids typically lead to the rapid and consistent induction of disease remission. Another promising therapeutic approach is B-cell depletion with rituximab. Although disease relapse is relatively common, provided that appropriate treatments are administered, ISC is considered a "benign" disease with a low risk of liver failure and biliary malignancy. Its molecular pathology is characterized by Th2-dominant immune reactions, regulatory T-cell activation, and CCL1-CCR8 interactions. Particular subsets of B cells such as plasmablasts and regulatory B cells also expand. A recent global proteomic study demonstrated that three significantly activated immunological cascades in ISC were all B-cell- or immunoglobulin-related (Fc-gamma receptor-mediated phagocytosis, B-cell receptor signaling pathway, and Fc-epsilon receptor I signaling pathway), suggesting the crucial roles of B cells in the underlying immune reactions. Despite the expansion of our knowledge of the pathophysiology of ISC, the exact role of IgG4 remains unclear. A better understanding of its immunopathology will offer some potential drug targets for this emerging biliary disease.

Inflammatory Myofibroblastic Tumors: Current Update

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm of intermediate biological potential with a predilection for the lung and abdominopelvic region. IMT represents the neoplastic subset of the family of inflammatory pseudotumors, an umbrella term for spindle cell proliferations of uncertain histogenesis with a variable inflammatory component. IMTs show characteristic fasciitis-like, compact spindle cell and hypocellular fibrous histologic patterns and distinctive molecular features. Imaging findings reflect pathologic features and vary from an ill-defined, infiltrating lesion to a wellcircumscribed, soft tissue mass owing to variable inflammatory, stromal, and myofibroblastic components.

Inflammatory pseudotumor of the liver occurring during the course of hepatitis C virus-related hepatocellular carcinoma treatment: A case report

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Occurrence of IPT of the liver during the course of HCC treatment is rare.

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IPT of the liver may resemble moderately differentiated HCC on dynamic enhanced CT.

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Hepatic IPT may be associated with latent inflammatory reactions to HCV activity despite negative HCV-RNA.

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Hepatectomy should be considered for a hepatic lesion suspected as HCC but may be IPT.

Introduction

Inflammatory pseudotumor (IPT) of the liver is a rare and benign disease that has a good prognosis. It is often difficult to distinguish IPT from hepatic malignancies, such as hepatocellular carcinoma (HCC), because specific clinical symptoms are absent and the diseases’ radiological findings can be similar. IPT is particularly difficult to distinguish from HCC in livers with hepatitis C virus (HCV)-related cirrhosis. We report a case of IPT of the liver that mimicked HCV-related HCC recurrence.

Presentation of case

A 78-year-old asymptomatic Japanese man who had undergone hepatectomy for HCV-related HCCs (moderately differentiated type) in segments 7 and 5 four and a half years previously was referred to our hospital for treatment of a 30-mm enhanced tumor in segment 5 (a typical HCC pattern). The tumor was identified via abdominal dynamic computed tomography (CT) and CT with hepatic arteriography and arterial portography. Thereafter, liver segmentectomy 5 was performed, and the histopathological diagnosis was a 10-mm IPT of the liver. After 1.5 years, magnetic resonance imaging revealed two new enhanced lesions in segment 8, which showed the typical pattern of HCC. Because these lesions grew in size for 3 months, liver segmentectomy 8 was performed for HCC recurrence. Histopathological examination showed that both lesions were HCCs.

Conclusion

HCV-related HCC has a high rate of multicentric recurrence. Our experience suggests that, when a hepatic lesion is suspected to be HCC, surgical resection should be considered for curative treatment and to rule out malignancy, even if the lesion may be an IPT.

New Thoughts on Immunoglobulin G4-Related Sclerosing Cholangitis

Immunoglobulin G4 (IgG4)-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation of the multisystem IgG4-related disease. IgG4-SC presents with biliary strictures and/or masses that can bear a striking similarity to other malignant and inflammatory diseases. Diagnosis is based on a combination of clinical, biochemical, radiological, and histologic findings with careful exclusion of malignant disease. Corticosteroids are the mainstay of treatment with good clinical, biochemical, and radiological responses. This review provides a comprehensive overview of the current knowledge of the prevalence, clinical features, radiology and histology findings, diagnosis, treatment, natural history, and pathophysiology of IgG4-SC.

The Histopathology of IgG4-Related Disease

IgG4-related disease is a multi-organ immune-mediated chronic fibroinflammatory condition characterized by elevated serum IgG4 concentrations, tumefaction, and tissue infiltration by IgG4-positive plasma cells. The exact etiology of IgG4-related disease remains unclear with no known role of the IgG4 molecule itself being identified. Although the pancreas and salivary glands are the main organs affected, the involvement of other organs has also been reported. This multi-organ disease mimics a large number of malignant, infectious, and inflammatory disorders; therefore, a prompt differential diagnosis is important for selecting the right therapeutic strategy. Early steroid therapy assists in preventing tissue fibrosis, parenchymal extinction, and severe functional impairments in the affected organs. The definitive and prompt diagnosis of IgG4-related disease requires both histopathological confirmation and clinicopathological correlations. A histopathological examination is mandatory to exclude neoplastic or inflammatory conditions that mimic IgG4-related disease. The histological changes that occur are basically similar in any organ manifestation, with several site-specific findings being recognized. This chapter summarizes general rules for the pathological examination of IgG4-related disease, as well as the histopathological features and differential diagnoses of major organ manifestations.

A case of hepatic inflammatory pseudotumor protruding from the liver surface

We report a case of a resected hepatic inflammatory pseudotumor (IPT) protruding from the liver surface. A 69-year-old male with diabetes mellitus was admitted to hospital for investigation of an hepatic mass. An irregularly shaped, low-echoic mass measuring 21 × 18 mm was identified by ultrasound in S6. On computed tomography, the tumor appeared to be growing extrahepatically. After contrast enhancement, the lesion showed persistent peripheral enhancement, while the central part was hypoenhanced. On T2-weighted magnetic resonance imaging (MRI), the central portion of the lesion was hyperintense compared with the periphery. EOB-enhanced MRI revealed the mass to be being hypointense in contrast to the surrounding liver parenchyma in the hepatobiliary phase. On diffusion-weighted images, the lesion was hyperintense. Percutaneous biopsy was not attempted to avoid tumor cell dissemination. The patient underwent partial hepatectomy because of suspected malignancy. Histopathological examination of the resected specimen revealed fibrotic tissue and abundant vessels in the periphery, while a massive infiltration of inflammatory cells and fewer vessels were observed in the center. The patient was finally diagnosed with hepatic IPT of the fibrohistiocytic type.

IgG4-related inflammatory pseudotumour mimicking a hepatic abscess impending rupture

A 50-year-old man presenting with sudden onset right upper quadrant pain and no constitutional symptoms was found to have two necrotic liver masses on imaging, consistent with hepatic abscesses unresponsive to systemic antibiotics and percutaneous drainage. The patient deteriorated and developed symptoms consistent with impending rupture. He therefore subsequently underwent right hepatic segmentectomy. All cultures were negative and histopathology confirmed IgG4 related disease/inflammatory pseudotumour of the liver. Postoperatively, the patient was asymptomatic with no IgG4 disease activity in other organs.

IgG4-Related Disease of the Gastrointestinal Tract: A 21st Century Chameleon

CONTEXT

Immunoglobulin G4 (IgG4)-related disease is a systemic fibroinflammatory disease capable of affecting virtually any organ. Although the pancreas and hepatobiliary system are commonly affected, involvement of the tubular gut is unusual. The pancreatic manifestations of this disease (autoimmune pancreatitis) often mimic pancreatic carcinoma, whereas the hepatobiliary manifestations are mistaken for cholangiocarcinoma or primary sclerosing cholangitis. The characteristic histologic features include a dense lymphoplasmacytic infiltrate, storiform-type fibrosis, and obliterative phlebitis. An increase in IgG4(+) plasma cells and an IgG4 to IgG ratio of more than 40% are considered obligatory components of the diagnostic algorithm.

OBJECTIVE

To review the challenges associated with the diagnosis of IgG4-related disease of the gastrointestinal tract.

DATA SOURCES

A review of pertinent literature, along with the author's personal experience, based on institutional and consultation materials.

CONCLUSION

The complete spectrum of histologic changes is seldom captured in a biopsy specimen, and thus, the histopathology findings are best interpreted within the overall clinical context. Increased IgG4(+) plasma cells are identified in a variety of benign and malignant diseases of the gastrointestinal tract.

IgG4 related sclerosing mastitis: expanding the morphological spectrum of IgG4 related diseases

IgG4 related disease (IgG4RD) is a recently recognised condition characterised by mass forming lesions associated with storiform fibrosis, obliterative phlebitis, lymphoplasmacytic infiltrate rich in IgG4 positive plasma cells and elevated serum IgG4 levels. Although rare, mammary involvement has been reported as IgG4 related sclerosing mastitis, the morphological counterpart of a growing family of IgG4 related diseases. A total of 17 cases belonging to mass forming benign inflammatory breast lesions such as plasma cell mastitis, granulomatous lobular mastitis, non-specific mastitis and inflammatory pseudotumour were investigated as a possible member of IgG4 related sclerosing mastitis. Clinical, radiological, histopathological and immunohistochemistry findings were noted in all cases. Cases diagnosed as inflammatory pseudotumour showed all the histopathological features of IgG4RD along with increased number of IgG4 positive plasma cells and IgG4/IgG ratio >40%. However, only a few IgG4 positive cells were seen in plasma cell mastitis, granulomatous lobular mastitis and non-specific mastitis cases. These cases also did not fulfill the morphological criteria for the diagnosis of IgG4 related diseases. IgG4RD should be excluded in plasma cell rich lesions diagnosed on core biopsies by IgG4 immunostaining. This can avoid unnecessary surgery as IgG4 related diseases respond to simple and effective steroid treatment.

Hepatic inflammatory pseudotumor presenting in an 8-year-old boy: A case report and review of literature

Hepatic inflammatory pseudotumors are uncommon benign lesions. Accurately diagnosing hepatic inflammatory pseudotumor can be very challenging because the clinical presentation and radiological appearances are nonspecific and cannot be certainly distinguished from malignant neoplastic processes. Herein, we present a case of hepatic IPT in an 8-year-old boy who presented to clinic with a 3-mo history of a tender hepatic mass, fever of unknown origin, and 9-kg weight loss. The physical examination was notable for tender hepatomegaly. Laboratory investigations were notable for a normal hepatic profile and elevated erythrocyte sedimentation rate and C-reactive protein. A T2-attenuated magnetic resonance imaging scan of the abdomen showed a 4.7 cm × 4.7 cm × 6.6 cm, contrast-enhancing, hyper-intense, well-defined lesion involving the right hepatic lobe. In view of the unremitting symptoms, tender hepatomegaly, thrombosed right hepatic vein, nonspecific radiological findings, and high suspicion of a deep-seated underlying infection or malignancy, a right hepatic lobectomy was recommended. Microscopically, the hepatic lesion exhibited a mixture of inflammatory cells (histiocytes, plasma cells, mature lymphocytes, and occasional multinucleated giant cells) in a background of dense fibrous tissue. Immunohistochemically, the cells stained negative for SMA, ALK-1, CD-21 and CD-23, diffusely positive for CD-68, and focally positive for IgG4. The final histopathological diagnosis was consistent with hepatic IPT. At the postoperative 4-mo follow-up, the patient was asymptomatic without radiological evidence of recurrence.

[Cholangitis with granulocytic epithelial lesion: a new entity with a specific treatment]

Herein, we report a case of cholangitis with granulocytic epithelial lesion associated with pancreatitis in a 22-year-old patient. The association of bile duct lesions and pancreatitis is usually very suggestive of IgG4 related disease. However, in our case, we found no IgG4 tissue infiltration and we found a granulocytic epithelial on the liver biopsy. Recently, cholangitis with granulocytic epithelial lesion was described in the literature. This entity is identified in 2 % of patients with sclerosing cholangitis. Patients are more likely children or young adults and often have an associated inflammatory bowel disease or rarely a pancreatitis. It is defined by the presence of neutrophilic bile duct lesions on a liver biopsy. Although rare, the diagnosis of cholangitis with granulocytic epithelial lesion is important because of its excellent response to immunosuppressive treatment.

The changing faces of IgG4-related disease: Clinical manifestations and pathogenesis

Since the earliest reports in 2001, immunoglobulin G4 (IgG4)-related disease has been defined as an autoimmune systemic disease characterized by the lymphoplasmacytic infiltration of affected tissues leading to fibrosis and obliterative phlebitis along with elevated serum IgG4 levels. Prior to this unifying hypothesis, a plethora of clinical manifestations were considered as separate entities despite the similar laboratory profile. The pathology can be observed in virtually all organs and may thus be a challenging diagnosis, especially when the adequate clinical suspicion is not present or when obtaining a tissue biopsy is not feasible. Nonetheless, the most frequently involved organs are the pancreas and exocrine glands but these may be spared. Immunosuppressants lead to a prompt clinical response in virtually all cases and prevent histological sequelae and, as a consequence, an early differential diagnosis from other conditions, particularly infections and cancer, as well as an early treatment should be pursued. We describe herein two cases in which atypical disease manifestations were observed, i.e., one with recurrent neck lymph node enlargement and proptosis, and one with jaundice. Our understanding of the pathogenesis of IgG4-related disease is largely incomplete but data support a significant role for Th2 cytokines with the contribution of innate immunity factors such as Toll-like receptors, macrophages and basophils. Further, macrophages activated by IL4 overexpress B cell activating factors and contribute to chronic inflammation and the development of fibrosis. We cannot rule out the possibility that the largely variable disease phenotypes reflect different pathogenetic mechanisms and the tissue microenvironment may then contribute to the organ involvement.

IgG4-related kidney disease from the renal pelvis that mimicked urothelial carcinoma: a case report

Background

IgG4-related kidney disease is a comprehensive term for renal lesions associated with IgG4-related disease, which mainly manifests as plasma cell-rich tubulointerstitial nephritis with increased IgG4+ plasma cells and fibrosis. IgG4-related kidney disease in the renal pelvis is rare.

Case presentation

We describe a 53-year-old Asian woman who was referred to our hospital with a space-occupying renal lesion discovered by medical examination. A physical examination and laboratory evaluation revealed no significant abnormalities. Computed tomography scans showed a soft-tissue mass with an irregular border and mild homogeneous enhancement in the right renal pelvis and calyces. A positron emission tomography/computed tomography scan revealed soft-tissue density shadows with increased radionuclide uptake. To investigate a suspected pelvic carcinoma, a right ureteronephrectomy was performed. A pathologic examination of the renal sections showed a dense lymphoplasmacytic infiltrate rich in IgG4+ plasma cells, with fibrosis beneath the urothelial epithelium of the renal pelvis. Postoperatively, the serum IgG4 level was significantly elevated. The patient was diagnosed with IgG4-related kidney disease.

Conclusion

We present a case of IgG4-related kidney disease mimicking urothelial carcinoma in the renal pelvis. When a buried and solitary hypovascular tumor is detected in the kidney, we must consider IgG4-related kidney disease as a differential diagnosis. Accordingly, elevated serum IgG4, radiologic findings, and pathologic examination may improve the diagnosis.

Clinicopathologic features of orbital immunoglobulin G4-related disease (IgG4-RD): a case series and literature review

BACKGROUND

Involvement of orbital structures by immunoglobulin G4-related disease (IgG4-RD) is not uncommon. We conducted this study to evaluate the clinicopathologic features of orbital IgG4-RD.

MATERIAL/METHODS

This was a retrospective, clinicopathologic study. Clinical records, light microscopic features, results of immunostaining with IgG & IgG4 and laboratory findings were reviewed in 16 patients diagnosed with orbital IgG4-RD.

RESULTS

Eleven patients had a bilateral disease, and the lacrimal gland was involved in 14. Dense sclerosis, plasma cell aggregates and dense lymphoplasmacytic infiltrate were seen in all patients. Serum IgG4 titre was elevated in 12 patients. Nine patients responded completely to glucocorticoid treatment. Five patients had a relapse on discontinuation of treatment.

CONCLUSION

Orbital IgG4-RD is a distinct clinicopathologic entity requiring increased awareness and needs to be differentiated from other orbital lymphoproliferative lesions.

Hepatic inflammatory pseudotumor associated with xanthogranulomatous cholangitis mimicking cholangiocarcinoma

Inflammatory pseudotumor (IPT) is a rare benign condition often misdiagnosed as malignancy. An 80-year-old man was referred to our clinic for an asymptomatic hepatic mass detected on plain abdominal CT. Abdominal ultrasonography identified the lesion as a poorly defined hypoechoic mass. Although a liver biopsy did not provide any evidence of malignancy, imaging modalities suggested a diagnosis of cholangiocarcinoma. The patient underwent left lobectomy, and the pathological findings were consistent with the features of xanthogranulomatous cholangitis. This case is the first report of hepatic IPT originating from xanthogranulomatous cholangitis without symptoms and illustrates the importance of obtaining a preoperative diagnosis in order to avoid a misdiagnosis of malignant tumor.

High Serum IgG4 Concentrations in Patients with Hashimoto's Thyroiditis

Purpose. Since recent reports suggest that Hashimoto thyroiditis (HT) may be associated with IgG4-related disease, we aimed to find out whether the measurement of serum IgG4 allows for the identification of distinct types of HT, with different clinical, sonographic, and serologic characteristics. Methods. The group studied consisted of 53 patients with HT and 28 healthy individuals who underwent thyroid ultrasonography and body composition analysis. Serum concentrations of IgG4, TSH, anti-peroxidase antibodies (TPOAb), anti-TSH receptor antibodies, TNF-α, TGF-β1, Fas Ligand, TRAIL, and chemokines (CXCL9, CXCL11, and CXCL10) were measured by ELISA or radioimmunoassay. Results. The group with IgG4 level >135 IU/ml accounted for 32.5% of the patients. The signs of fibrosis were present in 27.0% of the high-IgG4 patients and in 9.1% of the normal-IgG4 group. The patients with elevated IgG4 required higher doses of L-thyroxine and had significantly lower level of TPOAb (P=0.02) than the non-IgG4-HT individuals and higher TNF-α level in comparison with the controls (P=0.01). Conclusions. Our results suggest that the measurement of serum IgG4 allows for an identification of patients with more rapid progression of HT, requiring higher doses of L-thyroxine. Low TPOAb level and the absence of coexisting autoimmune diseases may suggest distinct pathomechanism of this type of thyroiditis.

Inflammatory myofibroblastic tumours: a pictorial review

Objectives

To present the most important characteristics of inflammatory myofibroblastic tumours (IMTs) arising in different locations of the body with histological correlation.

Methods

To review the symptoms and main radiological findings of IMTs. On ultrasonography (US), these tumours can appear as hypoechoic or hyperechoic masses and a variable Doppler appearance with increased vascularity. Computed tomography (CT) and magnetic resonance (MR) are the most used imaging tools in their evaluation. On contrast-enhanced CT, IMTs can appear as homogeneous or heterogeneous lesions, with variable enhancement on delayed acquisitions due to fibrosis. These findings are also present on gadolinium contrast-enhanced MR. On T1-weighted and T2-weighted sequences, IMTs usually show low signal intensity reflecting also the presence of fibrotic tissue.

Results

To show the main clinical symptoms and radiological features of IMTs in different locations: head and neck, lung, genitourinary, hepatic, splenic, gastrointestinal tract, mesenteric, muskuloskeletal.

Conclusions

Although IMTs in some organs are not uncommon, they are not usually included in the differential diagnosis of masses. Their radiological features suggest malignant neoplasms, whereas they are not. Consequently, this is an underdiagnosed entity and only after an histological exam could a definitive diagnosis be achieved.

Teaching Points

• Their radiological features suggest malignant neoplasms, whereas they are not

• CT and MR imaging are the most used tools in their evaluation

• IMT is an underdiagnosed entity

• The definitive diagnosis is only after histological exam

Biliary and hepatic involvement in IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a multi-systemic disorder. IgG4-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation of the disease, often in association with autoimmune pancreatitis (AIP). Hepatic manifestations of IgG4-RD are less well described within the literature.

AIM

To examine and present an overview of IgG4-RD with a focus on the biliary and hepatic manifestations.

METHODS

An electronic search using Medline was performed. Search items included 'IgG4 multi-system disease, IgG4 associated cholangitis, IgG4 associated liver disease and autoimmune pancreatitis (AIP)'.

RESULTS

IgG4-RD is characterised by an IgG4-positive lymphoplasmacytic tissue infiltrate, storiform fibrosis and an obliterative phlebitis. The HISORt criteria may be used to establish the diagnosis and incorporate a multi-disciplinary approach involving histology, radiology, serum IgG4 levels and response to steroid therapy. IgG4-SC is the commonest extrapancreatic manifestation of type-1 AIP, while the hepatic manifestations remain poorly defined. Important differential diagnoses include primary sclerosing cholangitis, secondary sclerosing cholangitis, cholangiocarcinoma and pancreatic carcinoma. Current treatment regimens remain ill defined although steroid therapy is used first line unless contraindicated. Patients with relapsing disease or multifocal disease should be considered for azathioprine. Available data would also suggest a role for rituximab.

CONCLUSIONS

IgG4-related sclerosing cholangitis is a common manifestation of IgG4-related disease which requires a multi-disciplinary approach to establish the diagnosis. Differentiating IgG4-related sclerosing cholangitis from other conditions, both benign and malignant, is challenging, but vital. Steroids remain the mainstay of treatment. Our understanding of the pathogenesis of the hepatic manifestations of IgG4-related disease continues to evolve.

Isolated IgG4-related sclerosing cholangitis: a report of 9 cases

Extrahepatic bile ducts are the most commonly involved extrapancreatic organ site in patients with type 1 autoimmune pancreatitis. IgG4-related sclerosing cholangitis (IgG4-SC) alone, without evidence of pancreatic or other organ involvement, is uncommon and is difficult to distinguish from cholangiocarcinoma preoperatively. We describe 9 patients with isolated IgG4-SC over an approximate 10-year period, each clinically suspected to have cholangiocarcinoma. We examined the clinical, radiological, cytologic (including fluorescence in situ hybridization results), and histologic features. IgG and IgG4 immunohistochemistry were performed. All 9 patients were middle-aged men who presented with obstructive jaundice. The biliary strictures involved all parts of the extrahepatic biliary tree. Serum IgG4 was slightly elevated in three of eight patients. Cytologic findings were interpreted as negative in six, atypical in one, and suspicious for adenocarcinoma in one. Fluorescence in situ hybridization revealed aneuploidy in one and was equivocal (trisomy 7) in 2. Eight of 9 patients underwent radical resection for suspected cholangiocarcinoma. There was only one case diagnosed with IgG4-SC preoperatively based on biopsy. Histologic sections revealed a prominent lymphoplasmacytic infiltrate with storiform fibrosis and marked increased IgG4-positive plasma cells (≥30/high-power field) in all specimens. Fifty percent of cases (4/8) had IgG4/IgG plasma cell ratio >40%. On median follow-up of 2.8 years, no relapse has occurred in any patient. Extrahepatic IgG4-SC may present as an isolated lesion mimicking cholangiocarcinoma. The diagnosis can be challenging. Clinicians and pathologists should recognize this to avoid major surgery.

Histological evaluation of obliterative phlebitis for the diagnosis of autoimmune pancreatitis

BACKGROUND

Obliterative phlebitis is a useful pathological finding for the diagnosis of lymphoplasmacytic sclerosing pancreatitis (LPSP), or type 1 autoimmune pancreatitis. The present study evaluated histological findings of obliterative phlebitis, including the significance of adding Elastica van Gieson stain (EVG) in comparison with other pancreatic conditions.

METHODS

Specimens of LPSP (n = 18), chronic pancreatitis (CP; n = 24), and pancreatic ductal adenocarcinoma (PDA; n = 45) were enrolled. Obliterative venous lesions (OVLs), defined as the presence of inflammatory cells and/or fibrosis inside the tunica adventitia, were counted and compared between hematoxylin and eosin stain (H&E) and EVG. OVLs were classified into three types: OVL-1, lymphoplasmacytic infiltration and fibrosis against a loose textured background; OVL-2, dense fibrosis with minimal or no lymphoplasmacytic infiltration; and OVL-3, densely packed lymphoplasmacytic infiltration without fibrosis. OVL type and OVL size were compared between disease groups.

RESULTS

OVL counts in LPSP, CP, and PDA were significantly higher with EVG than with H&E (p < 0.001). OVL-1 was most common in LPSP (H&E 92.4 %, EVG 79.8 %), and was identified in almost all cases of LPSP, but was less common in CP and PDA. Maximum diameter and OVL count in 1 cm(2) of OVL-1 were high for LPSP. Maximum diameter of OVL-1 ≥150 μm was observed in 17 LPSP, 0 CP, and 1 PDA cases (sensitivity 94.4 %, specificity 98.6 %).

CONCLUSIONS

Additional EVG is useful for excluding conditions mimicking OVL-1 or detecting OVL in small specimens. The presence of OVL-1 with diameter ≥150 μm is highly diagnostic for LPSP.

Serum levels of IgG and IgG4 in Hashimoto thyroiditis

Although IgG4-related disease is characterized by extensive infiltration of IgG4-positive plasma cells and lymphocytes of various organs, the details of this systemic disease are still unclear. We screened serum total IgG levels in the patients with Hashimoto thyroiditis (HT) to illustrate the prevalence of IgG4-related thyroiditis in HT. Twenty-four of 94 patients with HT (25.5%) had elevated serum IgG levels and their serum IgG4 was measured. Five of the 24 cases had more than 135 mg/dL of IgG4, which is the serum criterion of IgG4-related disease. One was a female patient who was initially treated as Graves' disease and rapidly developed a firm goiter and hypothyroidism. The biopsy of her thyroid gland revealed that follicular cells were atrophic with squamous metaplasia, replaced with fibrosis, which was compatible with the fibrous variant of HT. Immunohistochemical examination revealed diffuse infiltration of IgG4-positive plasma cells, and the serum IgG4 level was 179 mg/dL. The levels of IgG and IgG4 were positively correlated with the titers of anti-thyroglobulin antibody or anti-thyroid peroxidase antibody. In conclusion, at least a small portion of patients with HT with high titers of anti-thyroid antibodies may overlap the IgG4-related thyroiditis.

Inflammatory Myofibroblastic Tumor of the Liver: A Diagnostic Challenge

Inflammatory myofibroblastic tumor (IMT) is an uncommon myofibroblastic neoplasm that was formerly included within the broad category of inflammatory pseudotumor (IPT). IMT is rarely encountered in the liver. Similar to IMT of other organs, the interchangeable use of the terms IMT and IPT in liver has made the analysis of these lesions difficult. In this review, clinical and pathological features of IMT of the liver are reviewed and the differential diagnosis of IMT is discussed, with emphasis on IPT and the other entities included in this large category. IMT can mimic malignant tumors. There are no known unique diagnostic clinical, laboratory, or radiological features. The definitive diagnosis of IMT depends on careful pathological examination. The histopathological evaluation of hepatic IMT reveals that, the myxoid/vascular pattern is the most frequently observed, followed by, in decreasing frequency, fibrous histiocytoma-like pattern and hypocellular fibrous pattern. In IMT of the liver, anaplastic lymphoma kinase (ALK) expression reliably predicts the presence of an ALK gene rearrangement. The diagnosis of hepatic IMT depends on the dominant histopathological pattern, and the management of the disease is still controversial. IMT of the liver is a distinctive neoplasm of intermediate biological potential, and should be distinguished from the variety of lesions that are included under the broad category of IPT. Therefore, to avoid confusion regarding the true incidence and behavior of hepatic IMT, the term IPT should not be used interchangeably with IMT. The rarity of IMT in liver should not minimize its consideration in the differential diagnosis of liver tumors, especially in patients with tumor markers in normal range.

A classification of Hashimoto's thyroiditis based on immunohistochemistry for IgG4 and IgG

BACKGROUND

Hashimoto's thyroiditis (HT) is a common organ-specific autoimmune disease. Antithyroglobulin antibodies (TgAb) and antithyroperoxidase antibodies (TPOAb), predominantly of the immunoglobulin (Ig) G class, are hallmarks of HT. It has been reported that HT can be divided into IgG4 and non-IgG4 thyroiditis. The aim of our study was to investigate the meaning of this classification.

METHODS

Thyroid sections from 53 Hashimoto's patients with stored serum samples were collected to detect IgG4, IgG, α-smooth muscle actin, and transforming growth factor-β1 expression by immunohistochemical staining. The degree of fibrosis of thyroid parenchyma was qualitatively evaluated by Masson's trichrome. Serum total IgG, IgG4, TPOAb IgG, TgAb IgG, TPOAb IgG4, and TgAb IgG4 were detected by enzyme-linked immunosorbent assays (ELISAs).

RESULTS

Based on immunohistochemistry for IgG4 and IgG, 12 cases of IgG4-positive HT and 41 cases of IgG4-negative HT were identified in our study. The patients in the IgG4-positive HT group were significantly younger than those in the IgG4-negative HT group (p=0.023), and no significant differences were found in sex distribution, disease duration, and distribution of thyroid functional status between these two groups. The degree of fibrosis evaluated by Masson's trichrome and the immunohistochemical expression score of TGF-β1 in the IgG4-positive HT were significantly higher than those in the IgG4-negative HT (p<0.05). No significant differences were found in the levels of serum IgG4, total IgG, or IgG4/IgG ratio. However, TPOAb IgG4 and TgAb IgG4 levels and the ratios of TPOAb IgG4/TPOAb IgG, TgAb IgG4/TgAb IgG, TPOAb IgG4/IgG4, and TgAb IgG4/IgG4 were significantly higher in the IgG4-positive HT group than those in the IgG4-negative HT group respectively (p<0.05).

CONCLUSIONS

Our study indicates that HT can be divided into IgG4-positive and IgG4-negative HT, and this classification might have important clinical implications. The levels of IgG4 binding to specific thyroid antigens might be noninvasive markers to differentiate these two different immunophenotypes.

Increased immunoglobulin (Ig) G4-positive plasma cell density and IgG4/IgG ratio are not specific for IgG4-related disease in the skin

OBJECTIVES

Immunoglobulin (Ig) G4-related disease (IgG4-RD), a fibroinflammatory condition that can affect multiple organs, is suggested by lymphoplasmacytic inflammation, fibrosis, phlebitis, and increased IgG4+ plasma cell (PC) tissue density. In patients with suspected IgG4-RD and skin changes, skin biopsy may serve as a diagnostic screen or to supplement nondiagnostic visceral biopsy specimens. We aimed to determine whether increased cutaneous IgG4+ PCs or IgG4/IgG ratio is specific for IgG4-RD.

METHODS

We examined 50 mucocutaneous specimens representing seven PC-rich dermatoses and reactive PC-rich infiltrates with IgG and IgG4 immunohistochemical stains.

RESULTS

IgG4+ density exceeded 10 cells per high-power field in 22 (44%) of 50 specimens, representing six of seven diagnoses and reactive infiltrates. In five specimens (10%), the IgG4/IgG ratio exceeded 0.40.

CONCLUSIONS

Moderately elevated IgG4+ PC density or IgG4/IgG ratio is a nonspecific finding in the skin. In cutaneous biopsy specimens showing increased IgG4+ PCs, careful consideration should be given to clinical, serologic, and other histopathologic features before attributing clinical changes to IgG4-RD.