Association between IgG4-related disease and progressively transformed germinal centers of lymph nodes

From Castleman disease histopathological features to idiopathic multicentric Castleman disease: a multiparametric approach to exclude potential iMCD histopathological mimickers

AIMS

International consensus diagnostic criteria for idiopathic multicentric Castleman disease (iMCD) includes lymph node Castleman disease (CD) histopathological features as major criteria. Our aim was to apply those criteria in a series of 42 cases with CD to find differences among unicentric CD, iMCD, HHV-8+multicentric CD (HHV-8+MCD) and POEMS/plasma cell neoplasia (PCN)-associated CD.

METHODS

Available clinical and laboratory criteria were collected. Histopathological features (germinal centre hyperplasia/regression, plasmacytosis, hypervascularity and follicular dendritic cell (FDC) prominence) were graded and immunohistochemistry with antibodies against CD20, CD3, CD138, HHV-8, Ig isotype (IgG, IgG4, IgA, IgM, IgD), kappa, lambda was performed in all cases.

RESULTS

Fourteen cases had hyaline-vascular type unicentric CD, 15 were HHV-8+MCD, 7 cases PCN/POEMS-associated CD and 5 cases were iMCD. One case was consistent with systemic lupus erythematosus (SLE) lymphadenopathy. Differences in grading of the CD-associated histopathological features showed that FDC proliferation was prominent in unicentric CD, hypervascularity was increased in HHV-8 positive MCD and germinal centre hyperplasia was restricted to iMCD cases and SLE. Monotypic plasma cells were readily identifiable in the lymph node biopsies in 43% of PCN/POEMS-associated CD. All three cases had lambda light chain restriction with IgA (two cases) and IgG (one case) isotypes.

CONCLUSIONS

HHV-8+ MCD and PCN/POEMS-related CD are the major mimickers of iMCD in lymph node biopsies. Grading of the five histopathological features for CD might be useful to, in conjunction with complete ancillary testing, suggest for specific disease entities.

IgG4-related lymphadenopathy

IgG4-related lymphadenopathy is a nodal manifestation of IgG4-related disease (IgG4RD) which is characterized by increased polytypic IgG4+ plasma cells and IgG4+/IgG+ plasma cell ratio in lymph nodes and morphologically manifested as various patterns of reactive lymphadenopathy: Castleman disease-like, follicular hyperplasia, interfollicular expansion, progressive transformation of germinal centers and inflammatory pseudotumor-like. It typically presents with solitary or multiple, mild to moderate lymph node enlargement in otherwise asymptomatic patients. The serum IgG4 level is frequently elevated but C-reactive protein often remains normal. In patients not having a history of IgG4RD or manifestation of extranodal IgG4RD, a diagnosis of IgG4-lymphadenopathy should only be made with great caution given the non-specific morphologic features that can overlap with ANCA-associated vasculitis, interleukin-6 syndromes, Rosai-Dorfman disease, inflammatory myofibroblastic tumor, syphilis, lymphoma, and plasma cell neoplasia. Elevated IgG4 parameters, appropriate morphologies, and clinical correlation are essential to make the diagnosis of IgG4-lymphadenopathy more specific and clinically meaningful.

Clinical patterns and risk factors for multiorgan involvement in IgG4-Related disease patients

Background

IgG4-related disease with multiorgan involvement predicts higher disease activity, thus, it is necessary to identify whether IgG4-related disease involves multiple organs at the early stage. To further clarify the clinical characteristics and risk factors for IgG4-related disease with multiorgan involvement, we conducted an observational study.

Methods

We retrospectively analysed the clinical data of 160 patients who were primarily diagnosed with IgG4-related disease at the First Affiliated Hospital of Zhengzhou University from January 2015 to January 2021. According to the number of involved organs, patients were divided into two groups: multiorgan involvement and nonmultiorgan involvement. Patients were divided into a multiorgan group and a nonmultiorgan group according to multiple organ involvement.

Results

There were 82 cases identified with multiorgan involvement and 78 cases diagnosed with no multiorgan involvement in this series. Most cases were elderly and male (p > 0.05). The most frequently affected organs in IgG4-RD were the lymph nodes (50.6 %), pancreas (38.7 %) and salivary glands (35.6 %). Multivariate analysis showed that eosinophilia, IgG4>2*ULN, lymph node involvement, salivary gland involvement and lung involvement were independent risk factors for multiorgan involvement (p < 0.05).

Conclusions

The main issues in clinical practice are how to accurately diagnose the disease and screen the more vulnerable organs.

Reactive Lymphadenopathy in the Pediatric Population with a Focus on Potential Mimics of Lymphoma

Benign lymphadenopathy is common in the pediatric population and may be clinically striking. As in adults, lymph node evaluation in pediatric patients requires careful morphologic and immunohistochemical assessment and clinical contextualization of the findings. It is important for the pathologist to be familiar with benign and reactive conditions that may mimic malignancy. This review presents non-neoplastic or indolent processes or patterns of lymphoid hyperplasia that may be confused with or raise the differential of lymphoma, with a focus on those more commonly encountered in the pediatric/adolescent population.

Immunoglobulin G4-Related Disease, Lymphadenopathy, and Lymphoma

Lymphadenopathy occurring in patients with immunoglobulin G4 (IgG4)-related disease, termed IgG4-related lymphadenopathy, shows morphologic heterogeneity and overlap with other nonspecific causes of lymphadenopathy including infections, immune-related disorders, and neoplasms. This review describes the characteristic histopathologic features and diagnostic approach to IgG4-related disease and IgG4-related lymphadenopathy, with comparison to nonspecific causes of increased IgG4-positive plasma cells in lymph nodes, and with emphasis on distinction from IgG4-expressing lymphoproliferative disorders.

How I approach: The workup and management of patients with progressive transformation of the germinal center

Progressive transformation of the germinal center (PTGC) is a common and underrecognized cause of pediatric lymphadenopathy. PTGC may be associated with numerous systemic medical conditions that require further workup and management, including malignancy, autoimmune conditions, lymphoproliferative conditions, immunodeficiency, and infection. Given the breadth and rarity of the associated conditions, workup should be tailored to the individual patient and occur in a tiered approach. Patients with PTGC require ongoing follow-up, given their long-term risk of malignancy and recurrent PTGC.

[Reactive lymphadenopathies]

The human body comprises around 600 lymph nodes as constituents of a decentralized and dispersed immune system. The main task of lymph nodes is cleaning the lymph fluid and defending the organism against outer and inner threats by bacteria, viruses and tumour cells. The histologic picture of lymph nodes reflects the different strategies of the innate and adaptive immune system, which allocates antigen presenting cells, macrophages, B‑ and T‑cell systems and reticulum cells. However, the histological picture, without any additional investigations, usually only allows speculation about the causative agent like toxoplasmosis, other bacteria or viruses. This chapter describes different lymph node reactions in detail in order to obtain a better understanding of specific immune reactions allowing a precise diagnosis and a reliable distinction from malignant processes. The last issue in particular is one of the main tasks of haematopathology. In addition to these known principles, we try to integrate results obtained with the new method of three-dimensional (3D) microscopy of fixed lymphoid tissue. At first glance, this seems to be unusual. Nevertheless, we try to apply this approach, since 3D visualization of morphological details provides distinct cellular details as well as new interpretations of cell-cell interactions and the functions of lymphoid compartments, like germinal centres and T‑zones.

Active IgG4-related disease with bone marrow involvement: a report of 2 cases and case-based review

IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disease, histopathologically characterized by dense lymphoplasmacytic infiltration rich in IgG4-positive plasma cells in affected organs. Classic hematologic presentations including lymphadenopathy, eosinophilia and polyclonal hypergammaglobulinemia are common, whereas bone marrow involvement of IgG4-RD is rarely reported. Here we present two patients of multi-organ IgG4-RD with bone marrow involvement, one on bone marrow biopsy, and the other on PET/CT. Presentations of other organ involvement included biopsy-proven IgG4-related tubulointerstitial nephritis, lymphadenopathies, submaxillary glands, arteritis, asthma, dysosmia, and constitutional symptoms. Bone marrow involvement was initially suspected due to leukopenia, anemia and thrombocytopenia in case#1, and was finally confirmed by histological evidence of significant IgG4-positive plasma cells infiltration in bone marrow. In case#2, we incidentally observed high uptakes of multi-bone marrow on ¹⁸F-FDG-PET/CT, with the maximum SUV value similar to that of the kidneys, submaxillary glands and hilar, mediastinal lymph nodes by ¹⁸F-FDG-PET/CT. Symptoms and all the hematologic presentation improved rapidly in both patients after steroids initiation. These two cases illustrate the rare bone marrow involvement in active IgG4-RD accompanied by other hematologic syndromes. The significance of disease pathogenesis is worthy of further study.

Ossifying fibrous epulis as an IgG4-related disease of the oral cavity: a case report and literature review

Background

Fibrous sclerosing tumours and hypertrophic lesions in IgG4-related disease (IgG4-RD) are formed in various organs throughout the body, but disease in the oral region is not included among individual organ manifestations. We report a case of ossifying fibrous epulis that developed from the gingiva, as an instance of IgG4-RD.

Case presentation

A 60-year-old Japanese man visited the Department of Oral and Maxillofacial Surgery, Gunma University Hospital, with a chief complaint of swelling of the left mandibular gingiva. A 65 mm × 45 mm pedunculated tumour was observed. The bilateral submandibular lymph nodes were enlarged. The intraoperative pathological diagnosis of the enlarged cervical lymph nodes was inflammation. Based on this diagnosis, surgical excision was limited to the intraoral tumour, which was subsequently pathologically diagnosed as ossifying fibrous epulis. Histopathologically, the ossifying fibrous epulis exhibited increased levels of fibroblasts and collagen fibres, as well as infiltration by numerous plasma cells. The IgG4/IgG cell ratio was > 40%. Serologic analysis revealed hyper-IgG4-emia (> 135 mg/dL). The patient met the comprehensive clinical diagnosis criteria and the American College of Rheumatology and European League Against Rheumatism classification criteria for IgG4-RD. Based on these criteria, we diagnosed the ossifying fibrous epulis in our patient as an IgG4-related disease. A pathological diagnosis of IgG4-related lymphadenopathy was established for the cervical lymph nodes. Concomitant clinical findings were consistent with type II IgG4-related lymphadenopathy.

Conclusions

A routine serological test may be needed in cases with marked fibrous changes (such as epulis) in the oral cavity and plasma cells, accompanied by tumour formation, to determine the possibility of individual-organ manifestations of IgG4-related disease.

Light Chain-Restricted Plasmacytoid Cells in Hyperplastic Germinal CentersA Clinicopathologic Investigation

OBJECTIVES

Follicular hyperplasias (FHs) with light chain-restricted (LCR) plasmacytoid/plasma cells (PCs) within germinal centers (GCs) based on immunohistochemistry (IHC)/in situ hybridization (ISH) can potentially lead to diagnostic error. This study aims to better characterize such cases, including their clinical implications.

METHODS

LC expression by IHC/ISH was quantitatively assessed in GCs of 17 FHs with LCRGCs. BCL2, CD10, BCL6, BCL2, immunoglobulin (Ig) heavy chains, IgG4, and Epstein-Barr encoding region stains were performed. In total, 8 cases had polymerase chain reaction (PCR)-based clonality studies.

RESULTS

All cases showed FH, including 4 with progressively transformed GCs (PTGCs); 0.8% to 52% (median, 21%) of the GCs were LCR; 13 of 17 had both κ- and λ-LCRGCs, and 4 of 17 had only κ-LCRGCs; 7 of 16 had prominent intrafollicular IgG4-positive cells. One case demonstrated BCL2-positive cells in focal LCRGCs but lacked BCL2 rearrangement. B-cell monoclonality was demonstrated in 3 of 8 cases (only after microdissection). Seven patients had autoimmune disorders, and 1 had had a transplant. Three patients had a history of lymphoma, 1 developed lymphoma, and 1 developed lymphomatoid granulomatosis subsequently.

CONCLUSIONS

FHs with LCRGC by IHC/ISH are typically not associated with the development of lymphoma, even though they can express BCL2 and show monoclonality by PCR. They may be associated with increased intrafollicular IgG4-positive cells, PTGC, and autoimmunity.

Regional disturbance of the distribution of T regulatory cells and T helper cells associated with irregular-shaped germinal centers in immunoglobulin G4-related sialadenitis

Although many germinal centers (GCs) have been reported in immunoglobulin (Ig) G4-related disease, the significance of GCs in IgG4-related disease has not received attention. Both T follicular regulatory cells (Tfr), which are regulatory T cells (Treg) in GCs, and T follicular helper cells (Tfh) produce the cytokine interleukin (IL)-10 and regulate GC development. In whole-slide image analysis in surgical specimens using immunohistochemistry, IgG4-related sclerosing sialadenitis (IgG4-SS, n = 17) was characterized by markedly numerous, large, and irregular-shaped GCs with increased IL-10 + cells and Tfr and Tfh in the total area of the salivary gland compared with controls, including patients with chronic sialadenitis (n = 17) and Sjögren syndrome (n = 15). In particular, the central area of GC in IgG4-SS showed a higher Tfr number and Tfr/Tfh ratio than controls. The number of Tfr in the central area was significantly correlated with the number of IgG4 + plasmacytes and the number, size, and irregularity of GCs. In the mantle area, which surrounds GCs, IgG4-SS showed a higher Treg number and Treg/T helper cells (Th) ratio than controls. In IgG4-SS, the Treg/Th ratio was highest in the mantle area outside GCs and the Tfr/Tfh ratio was highest in the central area inside GCs. However, in controls, the Treg/Th ratio gradually decreased from outside to inside GCs. Our findings reveal that the morphological abnormality of GCs and the characteristic localization and altered balance of Treg and Th in the different compartments of inside and outside GCs would be the novel hallmarks of IgG4-SS.

IgG4-related Lymphadenopathy: A Comparative Study of 41 Cases Reveals Distinctive Histopathologic Features

Lymphadenopathy is common in patients with immunoglobulin G4-related disease (IgG4-RD). However, the described histopathologic features of IgG4-related lymphadenopathy have been shown to be largely nonspecific. In an attempt to identify features specific for nodal IgG4-RD we examined the histopathologic features of lymph nodes from 41 patients with established IgG4-RD, with comparison to 60 lymph nodes from patients without known or subsequent development of IgG4-RD. An increase in immunoglobulin (Ig) G4-positive plasma cells >100/HPF and IgG4/IgG ratio >40% was identified in 51% of IgG4-RD cases and 20% of control cases. Localization of increased IgG4-positive plasma cells and IgG4/IgG ratio to extrafollicular zones was highly associated with IgG4-RD, particularly when identified in regions of nodal fibrosis (P<0.0001; specificity: 98.3%), or in the context of marked interfollicular expansion (P=0.022; specificity: 100%). Other features characteristic of IgG4-RD included frequent eosinophils associated with IgG4-positive plasma cells, phlebitis (P=0.06), and perifollicular granulomas (P=0.16). The presence of an isolated increase in intrafollicular IgG4-positive plasma cells and IgG4/IgG ratio was more frequently present in control cases than IgG4-RD (P<0.0001). This study confirms that increased IgG4-positive plasma cells and IgG4/IgG ratio are neither sensitive nor specific for the diagnosis of IgG4-related lymphadenopathy, and most described morphologic patterns are nonspecific. In contrast, nodal involvement by IgG4-rich fibrosis akin to extranodal IgG4-RD or diffuse interfollicular expansion by IgG4-positive plasma cells are highly specific features of true IgG4-related lymphadenopathy. Our findings provide for a clinically meaningful approach to the evaluation of lymph nodes that will assist pathologists in distinguishing IgG4-related lymphadenopathy from its mimics.

Lymphadenopathy in IgG4-related disease: a phenotype of severe activity and poor prognosis, with eotaxin-3 as a new biomarker

Objective

To clarify relevant proteins and clinical characteristics of a phenotype of IgG4-related disease (IgG4-RD) with lymphadenopathy.

Methods

We enrolled patients newly diagnosed with IgG4-RD in our department between January 2000 and June 2018 and performed proteomic analysis to measure serum concentrations of 1305 proteins. We extracted proteins overexpressed in patients with IgG4-RD with lymphadenopathy by comparing between those with lymphadenopathy, those without lymphadenopathy and healthy controls. We further reviewed all the patients with IgG4-RD in our institution and investigated the characteristics and prognosis of the patients with IgG4-RD with lymphadenopathy.

Results

Eighty-five patients with IgG4-RD were enrolled, of which, 55% had lymphadenopathy. Proteomic analysis in 31 patients with IgG4-RD and 6 healthy controls revealed that eotaxin-3 was a potential serum biomarker in the patients with lymphadenopathy versus those without lymphadenopathy and healthy controls. A cohort of 85 patients with IgG4-RD demonstrated that patients with lymphadenopathy showed a significantly higher serum IgG4, IgG4:IgG ratio, IgG4-RD responder index and eosinophilia (P &lt; 0.001 for all), irrelevant of the extent to which organ involvement developed. Patients with lymphadenopathy treated with glucocorticoid alone relapsed with significantly higher rates than those without lymphadenopathy (P = 0.03).

Conclusion

Lymphadenopathy in IgG4-RD represents a phenotype associated with high disease activities, eosinophilia and relapsing disease. Eotaxin-3 is a novel biomarker related to IgG4-RD with lymphadenopathy.

Lymphocyte predominant Hodgkin lymphoma, antigen-driven after all?

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) was suggested as an entity separate from other types of Hodgkin lymphoma 40 years ago and recognized in the WHO classification in 2001. Based on its relatively benign course with late distant relapses, relation with lymph node hyperplasia with progressively transformed germinal centers, presence of clonal immunoglobulin gene rearrangements with somatic hypermutations and ongoing mutations, and relation with a number of inherited defects affecting the immune system, it has been suspected that NLPHL might be antigen-driven. Recent evidence has shown that cases of IgD-positive NLPHL are associated with infection by Moraxella catarrhalis, a common bacterium in the upper respiratory tract and in lymph nodes. This review summarizes the evidence for NLPHL as a B-cell lymphoma involving follicular T-lymphocytes normally found in germinal centers, its molecular features and relation to inherited immune defects, and its relation and differential diagnosis from similar entities. Finally, it discusses the evidence that in many cases a watch and wait policy might be a viable initial management strategy. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Increased IgG4-positive plasma cells in nodular-sclerosing Hodgkin lymphoma: a diagnostic pitfall

AIMS

Despite increasing interest in the recently established immunoglobulin 4-related disease (IgG4-RD), its pathogenesis and aetiology remain largely unclear. Characteristic histopathological features are one of the key elements of diagnosis, including 'storiform' fibrosis, obliterative phlebitis, increased lymphoplasmacytic infiltration and increased levels of IgG4 in serum and tissue. Histopathological features of IgG4-RD are striking but not specific, and can pose a pitfall for surgical pathologists. This paper aims to determine the actual amount of IgG4+ plasma cells in nodular-sclerosing Hodgkin lymphoma (NSHL) and its potential to be misdiagnosed in routine clinical practice.

METHODS AND RESULTS

IgG4+ plasma cells per high-power field (HPF) and the ratio of IgG4+ versus IgG+ plasma cells (IgG4/IgG ratio) in lymph node biopsies of 24 patients with nodular-sclerosing Hodgkin lymphoma (NSHL) were determined using immunohistochemistry and consensus scoring criteria as used for IgG4-RD. Ten lymph node biopsies with reactive follicular hyperplasia were assessed for comparison. Higher numbers of IgG4+ plasma cells (P < 0.001) were observed in NSHL versus follicular hyperplasia (mean 34 versus 8 per HPF) with a mean IgG4/IgG ratio of 0.38 versus 0.18. Five cases (21%) fulfilled the consensus criteria of IgG4-RD, with >50 IgG4+ plasma cells per HPF and an IgG4/IgG ratio of >0.4. The mean count of IgG4+ plasma cells per HPF in NSHL varied greatly (3-88) with increased numbers of IgG4+ plasma cells seen near areas of fibrosclerosis.

CONCLUSIONS

Significantly higher levels of IgG4+ plasma cells are common in NSHL, emphasising the need to exclude Reed-Sternberg cells by morphology and immunohistochemistry in biopsies where IgG4-RD is suspected.

A high number of IgG4-positive plasma cells rules out nodular lymphocyte predominant Hodgkin lymphoma

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a subtype of Hodgkin lymphoma that frequently shows a nodal growth pattern with abundant reactive B cells in the microenvironment. Early NLPHL cases can be particularly difficult to differentiate from progressively transformed germinal centers (PTGC). Since PTGC have been described to be IgG4 associated in a relatively high proportion of cases, the aim of the present study was to determine if IgG4 immunostaining can be helpful in the differential diagnosis between NLPHL and PTGC. We furthermore aimed to learn if LP cells can express IgG4. For this purpose, 58 cases of PTGC and 56 cases of NLPHL were assessed using IgG4 immunostaining. We could confirm that a significant number of PTGC cases showed high numbers of IgG4-positive plasma cells (22/58, 38%), whereas hot spot areas of IgG4-positive plasma cells were not found in any of the NLPHL cases. In lymph node areas with the differential diagnosis of NLPHL and PTGC, IgG4 immunostaining can therefore provide a helpful diagnostic tool to rule out NLPHL when a high number of IgG4-positive plasma cells are encountered. We also assessed 13 cases with a combination of NLPHL and PTGC in the same lymph node. Five of these cases presented hot spot areas of IgG4-positive plasma cells in the PTGC regions, while no significant numbers of IgG4-positive plasma cells were observed in the NLPHL part of the lymph node. LP cells were never IgG4 positive. Furthermore, immunoglobulin heavy chain rearrangements of single IgG4-positive plasma cells were analyzed, revealing a polyclonal plasma cell population. In summary, our data suggest that IgG4 immunostaining can provide additional information in the diagnostic workup of cases with the differential diagnosis of NLPHL and PTGC. IgG4's inefficiency in clearing antigens may explain why lymph nodes with PTGC are usually strongly enlarged and develop a high number of hyperplastic germinal centers. Polyclonal immunoglobulin heavy chain rearrangements in IgG4-positive plasma cells further support the hypothesis that PTGC represent a misled immune reaction.

Orbital progressive transformation of germinal centers as part of the spectrum of IgG4-related ophthalmic disease: Clinicopathologic features of three cases

Progressive transformation of germinal centers (PTGC) is a form of follicular hyperplasia recently associated with immunoglobulin G4-related disease (IgG4-RD), but the ophthalmic manifestations of this combination are poorly described. In this retrospective case series, we present three cases of IgG4-related orbital disease (IgG4-ROD) showing varying degrees of PTGC involving the orbit and lacrimal gland. Three adult women presented with ill-defined lacrimal gland enlargement. Histologic sections showed variable fibrosis and large, irregular lymphoid follicles with prominent mantle zones penetrating the germinal centers, highlighted by Bcl-2 and/or IgD immunostains. The interfollicular areas contained a mixture of plasma cells, scattered histiocytes and eosinophils. Mixed T and B-cells were present, and no signs of monoclonality were identified. All cases showed more than 100 IgG4 positive cells per high power field. Epstein-Barr virus in situ hybridization performed in one case was negative. The serum IgG4 level was tested in one case and showed elevation above the normal range. After 2–10 months of follow-up, the patients showed either near-complete resolution or no remaining signs of ophthalmic disease. Increasing awareness of these PTGC in extra-nodal locations, including the orbit, may provide a better understanding of the histologic spectrum of this disease.

Mast Cells Exhibiting Strong Cytoplasmic Staining for IgE and High Affinity IgE Receptor are Increased in IgG4-Related Disease

Immunoglobulin G4 (IgG4)-related disease is characterized by elevated serum IgG4 levels and increased numbers of IgG4-positive cells. However, its pathogenesis is not fully understood. We previously suggested that mast cells may play an important role in IgG4-related disease. In this study, we confirmed the characteristics of mast cells in IgG4-related lymphadenopathy by using immunohistochemistry and dual immunofluorescence. We analyzed 23 cases of IgG4-related lymphadenopathy and compared them with 23 cases of non-specific lymphoid hyperplasia. The majority of patients with IgG4-related lymphadenopathy had cervical lesions with involvement of other organs. Immunohistologically, mast cells with strong cytoplasmic staining for immunoglobulin E and high affinity immunoglobulin E receptor were significantly increased in IgG4-related lymphadenopathy as compared to those in non-specific lymphoid hyperplasia (mean: 3.83 ± 3.99 cells per high power field and 7.14 ± 8.21 cells per high power field, respectively; P = 0.007 and P = 0.011). In addition, dual immunofluorescence assay showed that immunoglobulin E and high affinity immunoglobulin E receptor staining exhibited a cytoplasmic granular pattern in IgG4-related lymphadenopathy, suggesting internalization of the antibodies and receptors. Our findings showed that mast cell activation might be involved in the pathogenesis of IgG4-related disease.

Imaging findings of primary immunoglobulin G4-related cervical lymphadenopathy

PURPOSE

The purpose of the present study was to assess imaging findings of primary immunoglobulin G4 (IgG4)-related cervical lymphadenopathy.

METHODS

Five consecutive patients with clinically, serologically, and histopathologically confirmed primary IgG4-related cervical lymphadenopathy without any other organ involvement were included. All patients underwent contrast-enhanced computed tomography (CT), and four underwent ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT. We retrospectively reviewed the images and assessed the number, size, location, central necrosis, perinodal infiltration, penetrating vessels, and maximum standardized uptake values (SUVmax) of the enlarged cervical nodes.

RESULTS

Thirteen enlarged cervical nodes measuring larger than 10 mm in minimum diameter were identified. The maximum and minimum diameter of enlarged nodes ranged from 1.2 to 3.2 cm (median, 1.8 cm) and from 1.0 to 1.9 cm (median, 1.2 cm), respectively. Lymphadenopathy was unilateral in all patients, and eight enlarged nodes were located at level IB (62%), one at level II (8%), three at level IV (23%), and one at level V (8%). Central necrosis was not seen in any nodes. Perinodal infiltration was seen in only one node (8%), and penetrating vessels were seen in seven nodes (54%). The median SUVmax of nine nodes was 4.45 (range, 2.08-12.44).

CONCLUSION

Eight enlarged nodes (62%) were located in the submandibular region. Central necrosis was not observed in any nodes and perinodal infiltration was observed in one node (8%).

[Update on nodular lymphocyte predominant Hodgkin's lymphoma and related lesions]

The present article gives an overview of novel developments in the diagnosis of nodular lymphocyte predominant Hodgkin's lymphoma with reference to the revised WHO classification from 2016. Differential diagnoses that are discussed are progressively transformed germinal centers, T cell/histiocyte-rich large B cell lymphoma as well as transformation into a diffuse large B cell lymphoma.

Therapeutic approach to IgG4-related disease: A systematic review

To review the reported evidence on the therapeutic management of IgG4-related disease (IgG4-RD) in clinical practice.A systematic search of the literature was conducted. The primary outcome measured was the rate of efficacy of first-line therapeutic approaches. Secondary outcomes measured included the rate of disease relapse, the outcome of untreated patients, the rate of patients without drug therapy at the end of follow-up, the rate of side effects, and mortality. The MOOSE, AHRQ, STROBE, and GRACE recommendations/statements were followed.The results of the systematic search strategy yielded 62 studies that included a total of 3034 patients. Complete information about first-line therapeutic regimens was detailed in 1952 patients, including glucocorticoid-based regimens in 1437 (74%), drug-free regimens in 213 (11%), and other therapies in 38 (2%). No therapy (wait and see management) was reported in 264 (13%) patients. The efficacy of monotherapy with glucocorticoids was specified in 1220 patients, of whom 97% had a therapeutic response. Relapses, however, were reported in 464/1395 (33%) patients despite typically short follow-up periods. Therapeutic efficacy was reported in 219/231 (95%) of relapses treated with glucocorticoids, 56/69 (81%) of those treated with azathioprine, 16/22 (72%) of those treated with other immunosuppressive agents, and in the 9 cases treated with rituximab (100%). In 14 studies, the authors detailed the outcome of 159/246 patients with wait-and-see management; spontaneous improvement or resolution was reported in 68 (43%) cases. Wide heterogeneity was observed with respect to the first-line therapeutic approaches used for the different organ-specific disease subsets, including significant differences in the mean dose of glucocorticoids used.Nearly 70% of reported IgG4-RD patients are treated with oral glucocorticoids in monotherapy. However, the therapeutic management is heavily influenced by geographical, epidemiological, and clinical factors, especially with respect to the predominant organ affected. The frequency of glucocorticoid failure to induce sustained remissions both during and after treatment and the assessment of glucocorticoid toxicity in IgG4-RD require further study.

Papillary Thyroid Cancer in a Child with Progressive Transformation of Germinal Centers

Objectives. To describe the presentation and management of a child with Progressive Transformation of Germinal Centers (PTGC), an uncommon condition characterized by significant persistent lymphadenopathy, who developed papillary thyroid carcinoma and to explore and review potential links between PTGC and neoplastic processes in the head and neck. Methods. Case presentation and literature review are used. Results. A 10-year-old female presented with a right parotid mass and cervical lymphadenopathy. Multiple biopsies revealed PTGC without malignancy. Two years later, she developed fatigue and weight gain, and a thyroid nodule was found. Fine needle aspiration was strongly suggestive of papillary thyroid carcinoma. The patient underwent total thyroidectomy and central neck dissection without surgical management of the longstanding right lateral neck lymphadenopathy. Final pathology confirmed papillary thyroid carcinoma. She was treated with radioactive iodine therapy postoperatively and remains free of disease at three years of follow-up. Conclusions. PTGC is considered a benign condition but has previously been associated with Nodular Lymphocyte Predominant Hodgkin Lymphoma (NLPHL). This is the first reported case of papillary thyroid cancer in a child with preexisting cervical PTGC and no defined risk factors for thyroid malignancy. No link has been established with thyroid carcinoma, but patients with PTGC may have a defect in immune surveillance that predisposes them to malignancy.

IgG4-producing lymphoma arising in a patient with IgG4-related disease

We herein report a case in which an IgG4-producing lymphoma arose in a patient with a previous diagnosis consistent with an IgG4-related disease. A 43-year-old man presented with enlarged cervical lymph nodes and was treated with steroids and radiation for what was initially assumed to be Kimura's disease, although the lesions were later histologically re-diagnosed as IgG4-related lymphadenopathy. Fourteen years later, when the patient was 58-years-old, he presented with retroperitoneal fibrosis and swollen lymph nodes. The suspicious lesions were not histologically examined as the patient did not give consent. However, the serum IgG4 concentration was high (1400 mg/dL) and he was clinically diagnosed with systemic IgG4-related disease. Although steroid administration reduced the size of the lesions, tapering the dose finally resulted in systemic, prominently enlarged lymph nodes. Analysis of the biopsy specimen revealed that these multiple lymph node lesions were marginal zone B cell lymphomas that themselves expressed IgG4. Complete remission was achieved after a total of six courses of chemotherapy including rituximab. This case suggests that the infiltrating IgG4-expressing cells observed in IgG4-related disease can clonally expand to malignant lymphomas.

A subset of ocular adnexal marginal zone lymphomas may arise in association with IgG4-related disease

We previously suggested a relationship between ocular immunoglobulin (Ig)G4-related disease (IgG4-RD) and marginal zone lymphomas (MZLs). However, the cytokine background associated with these disorders and whether it differs between ocular adnexal MZLs with (IgG4-associated MZL) and without (IgG4-negative MZL) numerous IgG4⁺ plasma cells are unknown. In this study, we identified the mRNA expression pattern of Th2 and regulatory T-cell (Treg) cytokines in IgG4-RD and in IgG4-associated MZL and IgG4-negative MZL using real-time polymerase chain reaction analysis. Ocular IgG4-RD and IgG4-associated MZL exhibited significantly higher expression ratios of interleukin (IL)-4/β-actin, IL-10/β-actin, IL-13/β-actin, transforming growth factor (TGF) β1/β-actin, and FOXP3/β-actin than did IgG4-negative MZL (p < 0.05). This finding further supports our prior observations that a significant subset of ocular MZLs arises in the setting of IgG4-RD. Furthermore, the presence of a different inflammatory background in IgG4-negative MZLs suggests that IgG4-associated MZLs may have a different pathogenesis.

Diagnostic Approach to the Complexity of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a systemic disease characterized by the infiltration of IgG4-bearing plasma cells and, more importantly, distinctive histopathological features: storiform fibrosis, obliterative phlebitis, a lymphoplasmacytic infiltrate, and mild-to-moderate tissue eosinophilia. The diagnostic approach is complex and relies on the coexistence of various clinical, laboratory, and histopathological findings, none of which is pathognomonic in and of itself. IgG4-related disease should be suspected in patients presenting with unexplained enlargement or swelling of 1 or more organs or tissue organs. Four laboratory abnormalities often provide initial clues to the diagnosis of IgG4-RD: peripheral eosinophilia, hypergammaglobulinemia, elevated serum IgE levels, and hypocomplementemia. Elevated serum IgG4 levels provided critical information in identifying the first cases of IgG4-RD, but recent studies have reported substantial limitations to the measurement of serum IgG4 concentrations, precluding reliance on serum IgG4 concentrations for diagnostic purposes. In contrast, new studies have suggested a promising role of flow cytometry studies in the diagnosis and longitudinal management of IgG4-RD. Demonstration of the classic histopathological features of IgG4-RD remains crucial to diagnosis in most cases, and biopsy proof is preferred strongly by most disease experts before the initiation of treatment. Of note, the multiorgan nature of IgG4-RD was first established in 2003. This review intends to provide most recent knowledge about the clinical, laboratory, radiological, and pathological characteristics of IgG4-RD that may guide the physician to establish an early diagnosis. We searched PubMed and MEDLINE for relevant articles published between January 1, 2000, and November 1, 2014, using the search terms IgG4 and IgG4-related.

The clinical spectrum of IgG4-related disease

IgG4-related disease (IgG4-RD) is an emerging immune-mediated disease with the capability of involving essentially any organ. The epidemiology of this disease has not been explored in detail. A majority of patients reported in the literature to date are from Japan, but the condition has been described all across the world and there is no strong evidence to suggest a predilection for Asian populations. The mean age at diagnosis is approximately 60 years and there is a decided male predominance for many clinical features, with an overall male:female ratio of 8:3. A cardinal feature of IgG4-RD is single or multiple organ swelling that often raises concern for malignancy. IgG4-RD should be suspected in patients presenting with unexplained enlargement or swelling of one or more organs. Presenting features vary substantially according to the specialty to which patients present first; in addition, the disease can be diagnosed unexpectedly in pathological specimens or identified incidentally on radiology studies. Involvement of major organs is common and IgG4-RD may lead to organ failure, particularly in the pancreas, liver and biliary tree, kidneys, thyroid gland, lungs, and aorta. The diagnosis of IgG4-RD relies on the coexistence of various clinical, laboratory and histopathological findings, although none is pathognomonic by itself.

T helper 2 and regulatory T-cell cytokine production by mast cells: a key factor in the pathogenesis of IgG4-related disease

IgG4-related disease is a systemic disorder with unique clinicopathological features and uncertain etiological features and is frequently related to allergic disease. T helper 2 and regulatory T-cell cytokines have been reported to be upregulated in the affected tissues; thus, the production of these cytokines by T helper 2 and regulatory T cells has been suggested as an important factor in the pathogenesis of IgG4-related disease. However, it is not yet clear which cells produce these cytokines in IgG4-related disease, and some aspects of the disorder cannot be completely explained by T-cell-related processes. To address this, we analyzed paraffin-embedded sections of tissues from nine cases of IgG4-related submandibular gland disease, five cases of submandibular sialolithiasis, and six cases of normal submandibular gland in order to identify potential key players in the pathogenesis of IgG4-related disease. Real-time polymerase chain reaction analysis confirmed the significant upregulation of interleukin (IL)4, IL10, and transforming growth factor beta 1 (TGFβ1) in IgG4-related disease. Interestingly, immunohistochemical studies indicated the presence of mast cells expressing these cytokines in diseased tissues. In addition, dual immunofluorescence assays identified cells that were double-positive for each cytokine and for KIT, which is expressed by mast cells. In contrast, the distribution of T cells did not correlate with cytokine distribution in affected tissues. We also found that the mast cells were strongly positive for IgE. This observation supports the hypothesis that mast cells are involved in IgG4-related disease, as mast cells are known to be closely related to allergic reactions and are activated in the presence of elevated non-specific IgE levels. In conclusion, our results indicate that mast cells produce T helper 2 and regulatory T-cell cytokines in tissues affected by IgG4-related disease and possibly have an important role in disease pathogenesis.

Systemic IgG4-related disease with extensive peripheral nerve involvement that progressed from localized IgG4-related lymphadenopathy: an autopsy case

A 77-year-old man, with a lengthy medical history of chronic dysuria, constipation, hypertension, myocardial infarction, and a submandibular lymphadenopathy that was excised 3 years ago, was hospitalized due to elevated liver enzyme levels. He demonstrated hypergammaglobulinemia, hyperproteinemia, high levels of IgG and IgG4, eosinophilia, sclerosing cholangitis, and retroperitoneal fibrosis. He was diagnosed with IgG4-related disease (IgG4-RD). While hospitalized, he had several episodes of syncope while standing and was diagnosed with autonomic nerve dysfunction. Thirty days after hospitalization, he died of nonocclusive mesenteric ischemia (NOMI). Post-mortem, his submandibular lymphadenopathy lesion was diagnosed with progressively transformed germinal center (PTGC)-type IgG4-related lymphadenopathy. At autopsy, small and large intestines showed mucosal necrosis and the wall muscles of the transverse to sigmoid colon were necrotic. The sigmoid colon was fibrotic and infiltrated with numerous IgG4+ plasma cells and eosinophils; infiltration into Auerbach's plexus was also observed. The IgG4-RD lesions were also detected in the mesentery of the sigmoid colon, retroperitoneal soft tissue, abdominal aorta, liver, extrahepatic bile duct, bilateral lungs, bilateral kidneys, urinary bladder, prostate, epicardium, bilateral coronary arteries, and lymph nodes. Interestingly, infiltration into the lesions was most notable around the peripheral nerves in every organ. Thus, this case describes an IgG4-RD that progressed from PTGC-type IgG4-related lymphadenopathy to systemic IgG4-RD, suggesting that IgG4-RD may affect many organs through peripheral nerve involvement.

VIRTUAL SLIDE

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9995992971155224.

Clinicopathologic analysis of IgG4-related skin disease

IgG4-related disease is a recently recognized systemic syndrome characterized by mass-forming lesions with lymphoplasmacytic infiltration, increase in the number of IgG4(+) cells in affected tissues and elevation of serum IgG4 levels. In 2009, we were the first to report skin lesions in patients with IgG4-related disease, but no large case series has been reported and clinicopathological findings remain unclear. To clarify these features, we herein report 10 patients (9 men and 1 woman; median age, 64 years; age range, 46-81 years) with IgG4-related skin disease. All patients had erythematous and itchy plaques or subcutaneous nodules on the skin of the head and neck, particularly in the periauricular, cheek, and mandible regions, except for one patient, whose forearm and waist skin were affected. In addition, eight patients had extracutaneous lesions: these were found on the lymph nodes in six patients, the lacrimal glands in three patients, the parotid glands in three patients, and the kidney in one patient. Histologically examined extracutaneous lesions were consistent with IgG4-related disease; five of six lymph node lesions showed progressively transformed germinal centers-type IgG4-related lymphadenopathy. Cases of IgG4-related skin disease were classified into two histological patterns: those exhibiting a nodular dermatitis pattern and those with a subcutaneous nodule pattern. The infiltrate was rich in plasma cells, small lymphocytes, and eosinophils; the majority of the plasma cells were IgG4(+). The IgG4(+) cell count was 49-396 per high-power field (mean±s.d., 172±129), with an IgG4(+)/IgG(+) cell ratio ranging from 62 to 92%. Serum IgG4 levels were elevated in all examined patients. In conclusion, patients with IgG4-related skin disease had uniform clinicopathology. Lesions were frequently present on the skin of the periauricular, cheek, and mandible regions, and were frequently accompanied by IgG4-related lymphadenopathy.

IgG4-related disease of the head and neck

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

Lymphadenopathy of IgG4-related disease: an underdiagnosed and overdiagnosed entity

Lymphadenopathy is a common occurrence in IgG4-related disease; it can appear before, concurrent with, or after the diagnosis of this disease, which is characterized by tumefactive sclerosing inflammatory lesions predominantly affecting extranodal sites, such as the pancreas, salivary gland, and lacrimal gland. Although multiple lymph node groups are commonly involved, constitutional symptoms are absent. The lymph nodes can show a broad morphologic spectrum, including multicentric Castleman disease-like (type I), follicular hyperplasia (type II), interfollicular expansion (type III), progressive transformation of germinal centers (type IV), and inflammatory pseudotumor-like (type V). All are characterized by an increase in IgG4+ plasma cells (>100 per high power field) and IgG4/IgG ratio (>40%). IgG4-related lymphadenopathy is both an underdiagnosed and overdiagnosed entity. The former is because of the fact that this entity has not been characterized until recently, while the latter results from pathologists' enthusiasm in diagnosing "new" entities and the lack of specificity of the morphologic and immunophenotypic features of IgG4-related lymphadenopathy. It is prudent to render this diagnosis only for patients with known IgG4-related disease or in the presence of corroborating clinical and laboratory findings (such as elderly men, systemic lymphadenopathy, elevated serum IgG4, IgG, and IgE but not IgM and IgA, and low titers of autoantibodies). Outside these circumstances, a descriptive diagnosis of "reactive lymphoid hyperplasia with increased IgG4+ cells" accompanied by a recommendation for follow-up will be appropriate because IgG4-related disease will likely ensue only in a minority of such patients.

IgG4-Related Lymphadenopathy

Lymphadenopathy is frequently observed in patients with immunoglobulin G4-related disease (IgG4-RD) and sometimes appears as the first manifestation of the disease. The diagnosis of IgG4-related lymphadenopathy is complicated owing to a great histological diversity, with at least 5 histological subtypes. Indeed, lymph node biopsy may be performed under the suspicion that the lymphadenopathy is a malignant lymphoma or other lymphoproliferative disorder. The diagnosis of IgG4-RD is characterized by both elevated serum IgG4 (>135 mg/dL) and histopathological features, including a dense lymphoplasmacytic infiltrate rich in IgG4(+) plasma cells (IgG4(+)/IgG(+) plasma cell ratio >40%). However, patients with hyper-interleukin (IL-) 6 syndromes such as multicentric Castleman's disease, rheumatoid arthritis, and other immune-mediated conditions frequently show lymph node involvement and often fulfill the diagnostic criteria for IgG4-RD. Owing to these factors, IgG4-RD cannot be differentiated from hyper-IL-6 syndromes on the basis of histological findings alone. Laboratory analyses are crucial to differentiate between the 2 diseases. Hyper-IL-6 syndromes are characterized by elevated serum levels of IgG, IgA, IgM, and C-reactive protein (CRP); thrombocytosis; anemia; hypoalbuminemia; hypocholesterolemia. In contrast, IgG4-RD does not share any of these characteristics. Therefore, the diagnosis of IgG4-RD requires not only pathological findings but also clinical and laboratory analyses.