Hyper-IgG4 disease: report and characterisation of a new disease

Immunoglobulin G4-positive plasma cell infiltration in explanted livers for primary sclerosing cholangitis

AIMS

To explore whether immunoglobulin (Ig)G4-related sclerosing cholangitis (IgG4-SC) contributes to end-stage primary sclerosing cholangitis (PSC) in the United Kingdom.

METHODS AND RESULTS

This study consisted of 41 patients who underwent liver transplantation for advanced PSC. Explanted livers were examined histologically with an emphasis on IgG4-positive plasma cell infiltration. Thirty-nine cases (95%) had minimal or mild infiltration of IgG4-positive plasma cells (≤ 30 cells/high-power field). In contrast, two cases (5%) showed plasma cell IgG4-positivity in more than 100 cells/high-power field. IgG4-positive plasma cells were accumulated preferentially in a (xantho)granulomatous tissue within large bile ducts. Except for the presence of IgG4-positive plasma cells, there was no significant histological difference between IgG4-positive and negative cases. Both showed sclerosing cholangitis with bile duct erosion and xanthogranulomatous reaction more in keeping with PSC than typical IgG4-SC. Clinically, the two patients differed from typical IgG4-related disease, in that both had associated ulcerative colitis, and one of them was younger than expected for IgG4-SC (28 years old).

CONCLUSIONS

No classical IgG4-SC could be identified in patients explanted for PSC. The two cases identified with numerous IgG4-positive plasma cells suggest a superimposed immune mechanism of uncertain nature. A prospective study is needed to assess whether such cases will be steroid-sensitive.

Orbital necrobiotic xanthogranuloma associated with systemic IgG4 disease

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A case of IgG4-related disease with features of Mikulicz's disease, and retroperitoneal fibrosis and lymphadenopathy mimicking Castleman's disease

A 51-year-old man developed painless enlargement of the bilateral submandibular and lacrimal glands without xerostomia or xerophthalmia in the absence of autoantibodies to SS-A (Ro) and SS-B (La). In a few years, he developed generalized lymphadenopathy, with markedly elevated serum IgG4, and a computed tomography scan revealed soft-tissue-density lesions around the abdominal aorta, a finding consistent with retroperitoneal fibrosis. Biopsy of the cervical lymph node showed an expansion of the interfollicular area by heavily infiltrating plasma cells, consistent with multicentric Castleman's disease. Immunohistochemical analysis revealed that the IgG4-positive/IgG-positive plasma cell ratio was 80%, leading us to a single diagnosis of IgG4-related disease. High-dose corticosteroid treatment resulted in prompt resolution of the physical, serological, and imaging abnormalities. Although IgG4-related disease can mimic multicentric Castleman's disease, as in our patient, the two diseases have effective but distinct treatments, and thus measurement of serum IgG4 levels and specific immunohistochemical analysis for determining the IgG4-positive/IgG-positive plasma cell ratio are recommended if IgG4-related disease is suspected.

Successful treatment of pediatric IgG4 related systemic disease with mycophenolate mofetil: case report and a review of the pediatric autoimmune pancreatitis literature

Autoimmune pancreatitis is frequently associated with elevated serum and tissue IgG4 levels in the adult population, but there are few reports of pediatric autoimmune pancreatitis, and even fewer reports of IgG4 related systemic disease in a pediatric population. The standard of care treatment in adults is systemic corticosteroids with resolution of symptoms in most cases; however, multiple courses of corticosteroids are occasionally required and some patients require long term corticosteroids. In these instances, steroid sparing disease modify treatments are in demand. We describe a 13-year-old girl with IgG4 related systemic disease who presented with chronic recurrent autoimmune pancreatitis resulting in surgical intervention for obstructive hyperbilirubinemia and chronic corticosteroid treatment. In addition, she developed fibrosing medianstinitis as part of her IgG4 related systemic disease. She was eventually successfully treated with mycophenolate mofetil allowing for discontinuation of corticosteroids. This is the first reported use of mycophenolate mofetil for IgG4 related pancreatitis. Although autoimmune pancreatitis as part of IgG4 related systemic disease is rarely reported in pediatrics, autoimmune pancreatitis is also characterized as idiopathic fibrosing pancreatitis. All pediatric autoimmune pancreatitis cases reported in the world medical literature were identified via a PUBMED search and are reviewed herein. Twelve reports of pediatric autoimmune pancreatitis were identified, most of which were treated with corticosteroids or surgical approaches. Most case reports failed to report IgG4 levels, so it remains unclear how commonly IgG4 related autoimmune pancreatitis occurs during childhood. Increased evaluation of IgG4 levels in patients with autoimmune pancreatitis may shed further light on the association of IgG4 with pancreatitis and the underlying pathophysiology.

Successful treatment of pediatric IgG4 related systemic disease with mycophenolate mofetil: case report and a review of the pediatric autoimmune pancreatitis literature

Autoimmune pancreatitis is frequently associated with elevated serum and tissue IgG4 levels in the adult population, but there are few reports of pediatric autoimmune pancreatitis, and even fewer reports of IgG4 related systemic disease in a pediatric population. The standard of care treatment in adults is systemic corticosteroids with resolution of symptoms in most cases; however, multiple courses of corticosteroids are occasionally required and some patients require long term corticosteroids. In these instances, steroid sparing disease modify treatments are in demand. We describe a 13-year-old girl with IgG4 related systemic disease who presented with chronic recurrent autoimmune pancreatitis resulting in surgical intervention for obstructive hyperbilirubinemia and chronic corticosteroid treatment. In addition, she developed fibrosing medianstinitis as part of her IgG4 related systemic disease. She was eventually successfully treated with mycophenolate mofetil allowing for discontinuation of corticosteroids. This is the first reported use of mycophenolate mofetil for IgG4 related pancreatitis. Although autoimmune pancreatitis as part of IgG4 related systemic disease is rarely reported in pediatrics, autoimmune pancreatitis is also characterized as idiopathic fibrosing pancreatitis. All pediatric autoimmune pancreatitis cases reported in the world medical literature were identified via a PUBMED search and are reviewed herein. Twelve reports of pediatric autoimmune pancreatitis were identified, most of which were treated with corticosteroids or surgical approaches. Most case reports failed to report IgG4 levels, so it remains unclear how commonly IgG4 related autoimmune pancreatitis occurs during childhood. Increased evaluation of IgG4 levels in patients with autoimmune pancreatitis may shed further light on the association of IgG4 with pancreatitis and the underlying pathophysiology.

Hypocomplementemic urticarial vasculitis syndrome is associated with high levels of serum IgG4: a clinical manifestation that mimics IgG4-related disease

A 58-year-old Japanese woman presented with recurrent abdominal pain, chronic urticaria, and petechiae on her extremities, and hypocomplementemia, findings that were consistent with hypocomplementemic urticarial vasculitis syndrome (HUVS). A laboratory examination revealed that she had markedly elevated IgG levels (4,448 mg/dL; normal range, 870-1,700 mg/dL) with particularly high IgG4 levels (1,050 mg/dL; normal range, 48-105 mg/dL) and a high IgG4/total IgG ratio (0.22; normal range, 0.02-0.05). A skin biopsy demonstrated leukocytoclastic vasculitis with IgG4 deposition in the vascular lumen and vascular walls. A lymph node biopsy revealed reactive lymphoid hyperplasia with numerous IgG4-positive cells in the perifollicular area, but no sclerotic findings. A chromosomal analysis of an enlarged lymph node, without phytohemagglutinin (PHA) stimulation, demonstrated that one in every three analyzed cells had abnormalities, such as 44, XX, -13, add(15)(p11), -17, -17, and mar.

IgG4-related systemic disease in a Native American man

IgG4-related systemic disease is a recently described entity that can elude even the most astute diagnostician. Patients with the disease, characterized by the infiltration of polyclonal IgG4-positive plasmacytes, can present with single or multi-organ involvement. Manifestations include dacryoadenitis, sialadenitis, thyroiditis, pneumonitis, retroperitoneal fibrosis, pancreatitis, sclerosing cholangitis, tubulointerstitial nephritis, prostatitis, and hypophysitis. We describe a biopsy-confirmed case with extensive multi-organ involvement, including hypophysitis, dacryoadenitis, retroperitoneal fibrosis and tubulointerstitial nephritis. By reporting this case, we hope to bring IgG4-related systemic disease to the attention of the broader medical community as it is an elusive disease that commonly responds to systemic corticosteroids.

Aortitis and periaortitis in ankylosing spondylitis

Aortic involvement is a potential life-threatening complication of ankylosing spondylitis, usually occurring late in the course of this frequent disease. Inflammatory lesions evolving to fibrosis are primarily localized in the aortic root causing regurgitation, but this process can extend into the left atrium (subaortic bump) involving the mitral valve and the heart conduction system. First, second and third degree atrioventricular blocks are the most common conduction alterations described and they can be temporary. Chronic periaortitis has been described in ankylosing spondylitis patients. This disease is characterized by inflammation evolving to fibrosis and it is localized in the periaortic and peri-iliac retroperitoneum. It causes compressive effects on ureters and venous, arterial and lymphatic vessels. Its treatment employs endoscopic and/or surgical procedures and administration of corticosteroids, even in association with immunosuppressive agents. Both aortitis (with conduction system alterations) and periaortitis should be kept in mind by the physicians because they can significantly influence the prognosis of ankylosing spondylitis patients and they can need a rapid treatment.

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

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

Gastric IgG4-Related Autoimmune Fibrosclerosing Pseudotumour: A Novel Location

We describe the first reported case of an IgG4-related autoimmune fibrosclerosing pseudotumour located in the stomach of a 75-year old woman presenting with weight loss and vomiting. A lesion was detected in the gastric body at endoscopy. Subsequent characterisation by CT was suggestive of a gastrointestinal stromal tumour. Following laparoscopic resection, the patient recovered uneventfully. Histological examination of the resected specimen revealed an IgG4-related fibrosclerosing pseudotumour, a novel location for this histopathological entity.

Riedel's thyroiditis and multifocal fibrosclerosis are part of the IgG4-related systemic disease spectrum

OBJECTIVE

Riedel's thyroiditis is a chronic fibrosing disorder of unknown etiology often associated with "multifocal fibrosclerosis." IgG4-related systemic disease is characterized by IgG4+ plasma cell infiltration and fibrosis throughout many organs. We hypothesized that Riedel's thyroiditis is part of the IgG4-related systemic disease spectrum.

METHODS

We searched our institution's pathology database using the terms "Riedel's," "struma," "thyroid," and "fibrosis," and identified 3 cases of Riedel's thyroiditis. Riedel's thyroiditis was diagnosed if there was a fibroinflammatory process involving all or a portion of the thyroid gland, with evidence of extension of the process into surrounding tissues. Immunohistochemical stains for IgG4 and IgG were performed. The histopathologic and immunohistochemical features of each involved organ were evaluated. The clinical features of one patient with multiple organ system disease were described.

RESULTS

All 3 thyroidectomy samples stained positively for IgG4-bearing plasma cells. One patient had extensive extrathyroidal involvement diagnostic of IgG4-related systemic disease, including cholangitis, pseudotumors of both the lung and lacrimal gland, and a lymph node contiguous to the thyroid that stained intensely for IgG4+ plasma cells. The histologic features of all organs involved were consistent with IgG4-related systemic disease. Patient 3 had 10 IgG4+ plasma cells per high-power field initially, but rebiopsy 2 years later demonstrated no IgG4+ plasma cells. That patient's second biopsy, characterized by fibrosis and minimal residual inflammation, further solidifies the link between IgG4-bearing plasma cells in tissue and the histologic evolution to Riedel's thyroiditis.

CONCLUSION

Riedel's thyroiditis is part of the IgG4-related systemic disease spectrum. In many cases, multifocal fibrosclerosis and IgG4-related systemic disease are probably the same entity.

Paratesticular fibrous pseudotumor--an IgG4-related disorder?

Paratesticular fibrous pseudotumor (nodular periorchitis, inflammatory pseudotumor of the spermatic cord) is a rare, benign condition of unknown etiology characterized by solitary or multiple intrascrotal nodules composed of dense fibrous tissue with a variable, sometimes sparse inflammatory infiltrate. Based on certain similarities to other fibroinflammatory disorders characterized by infiltrates of IgG4-expressing plasma cells and recently subsumed under the heading of IgG4-mediated diseases, we investigated the plasma cell distribution and immunoglobulin isotypes in three cases of paratesticular fibrous and inflammatory pseudotumor. All three cases showed a high number of IgG4-positive plasma cells with an IgG4 to IgG ratio of 44-48%. This finding indicates that paratesticular fibrous pseudotumor might belong to the growing list of IgG4-related diseases, which by now includes such diverse entities as retroperitoneal fibrosis, sclerosing pancreatitis and cholangitis, Riedel's thyroiditis, or sclerosing sialadenitis.

Radiological findings and clinical features of thoracic immunoglobulin G4-positive plasma cell granuloma: two cases

Plasma cell granulomas, inflammatory pseudotumours and myofibroblastomas are synonymous with characteristic plasma cell infiltration in various body organs including the pancreas, liver, retroperitoneum and mediastinal structures causing idiopathic fibrosclerosis. Recently, a new concept has arisen regarding the relationship between immunoglobulin (Ig)G4-positive cell infiltration and idiopathic systemic fibrosclerosis. We report two cases showing IgG4-positive cell infiltration in the lung presenting as lung nodules with or without extrapulmonary manifestations.

IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity

An elevated serum titer of immunoglobulin G4 (IgG4), the least common (3% to 6%) of the 4 subclasses of IgG, is a surrogate marker for the recently characterized IgG4-related sclerosing disease. The syndrome affects predominantly middle-aged and elderly patients, with male predominance. The patients present with symptoms referable to the involvement of 1 or more sites, usually in the form of mass lesions. The prototype is IgG4-related sclerosing pancreatitis (also known as autoimmune pancreatitis), most commonly presenting as painless obstructive jaundice with or without a pancreatic mass. Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, but practically any organ-site can be affected, such as retroperitoneum, aorta, mediastinum, soft tissue, skin, central nervous system, breast, kidney, prostate, upper aerodigestive tract, and lung. The patients usually have a good general condition, with no fever or constitutional symptoms. Common laboratory findings include raised serum globulin, IgG, IgG4, and IgE, whereas lactate dehydrogenase is usually not raised. Some patients have low titers of autoantibodies (such as antinuclear antibodies and rheumatoid factor). The disease often shows excellent response to steroid therapy. The natural history is characterized by the development of multiple sites of involvement with time, sometimes after many years. However, the disease can remain localized to 1 site in occasional patients. The main pathologic findings in various extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, accompanied by atrophy and loss of the specialized structures of the involved tissue (such as secretory acini in pancreas, salivary gland, or lacrimal gland). The relative predominance of the lymphoplasmacytic and sclerotic components results in 3 histologic patterns: pseudolymphomatous, mixed, and sclerosing. Immunostaining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). The lymph nodes show multicentric Castleman disease-like features, reactive follicular hyperplasia, interfollicular expansion, or progressive transformation of germinal centers, with the unifying feature being an increase in IgG4+ plasma cells on immunostaining. The nature and pathogenesis of IgG4-related sclerosing disease are still elusive. Occasionally, the disease can be complicated by the development of malignant lymphoma and possibly carcinoma.

Unifocal and multifocal reactive lymphoid hyperplasia vs follicular lymphoma of the ocular adnexa

PURPOSE

To characterize the differentiating histopathologic and immunophenotypic features of reactive lymphoid hyperplasia (RLH) and follicular lymphoma of the ocular adnexa.

DESIGN

Retrospective case study with clinical follow-up and review of the literature.

METHODS

Clinical records of 9 cases of RLH and 6 cases of follicular lymphoma from 2 institutions were reviewed. Light microscopic evaluation and immunohistochemical stains including CD20, CD3, CD5, CD21, CD23, BCL-2, BCL-6, CD10, kappa, lambda, and Ki67 were used to distinguish the 2 categories.

RESULTS

RLH preferentially involved the conjunctiva, whereas follicular lymphoma had a propensity to involve the lacrimal gland. Microscopic analysis with immunohistochemical staining distinguished RLH from follicular lymphoma. BCL-2 was positive in follicular centers of follicular lymphoma but not in RLH. CD10 identified follicular center cells and Ki67 quantified cells in S-phase. CD21 and CD23 detected dendritic cell scaffoldings of indistinct germinal centers. None of the patients with RLH developed lymphoma during their clinical courses (up to 18 years). However, 3 patients with orbital, but not conjunctival, RLH developed immunohistochemically proven multifocal nonophthalmic supradiaphragmatic adnexal RLH (sites included lung, parotid, axillary nodes, and uvea). All 6 patients with follicular lymphoma had disseminated disease.

CONCLUSIONS

A correct diagnosis of RLH vs follicular lymphoma can be reliably established employing immunohistochemical methods. A heretofore undescribed "multifocal RLH" syndrome must be distinguished from follicular lymphoma. Conjunctival RLH can usually be managed surgically without radiotherapy, but "multifocal RLH" required systemic treatment in 2 of 3 patients. Follicular lymphoma requires systemic chemotherapy if discovered beyond stage 1E.

Treatment with bortezomib of a patient having hyper IgG4 disease

Hyper IgG4 disease is a recently described inflammatory disease characterized by lymphoplasmacytic infiltration leading to fibrosis and tissue destruction. Whereas most cases have been successfully treated with corticosteroids, recurrent or refractory cases may benefit from alternative therapies. Bortezomib has proven to be successful in the treatment of multiple myeloma, and its mechanism indicates that it may have merit in autoimmune or other plasmacytic disorders. We report a patient with recurrent pulmonary infiltration with IgG4 plasma cells, consistent with hyper IgG4 disease, who was successfully treated using a bortezomib-based combination with minimal therapy-related toxicities.

Immunoglobulin G4 related systemic sclerosing disease involving the temporal bone

Objective:

To report a rare condition affecting the temporal bone. Immunoglobulin G4 related systemic sclerosing disease is a recently described autoimmune condition with manifestations typically involving the pancreas, biliary system, salivary glands, lungs, kidneys and prostate. Histologically, it is characterised by T-cell infiltration, fibrosis and numerous immunoglobulin G4-positive plasma cells. This condition previously fell under the umbrella diagnosis of inflammatory pseudotumour and inflammatory myofibroblastic tumour.

Case report:

We present the case of a 58-year-old woman with multiple inflammatory masses involving the pharynx, gall bladder, lungs, pelvis, omentum, eyes and left temporal bone, over a seven-year period. We describe this patient's unusual clinical course and pathological features, which resulted in a change of diagnosis from metastatic inflammatory myofibroblastic tumour to immunoglobulin G4 related systemic sclerosing disease. We also review the literature regarding the management of inflammatory pseudotumours of the temporal bone, and how this differs from the management of immunoglobulin G4 related systemic sclerosing disease.

Conclusion:

We would recommend a full review of all histological specimens in patients with a diagnosis of temporal bone inflammatory pseudotumour or inflammatory myofibroblastic tumour. Consideration should be given to immunohistochemical analysis for anaplastic lymphoma kinase and immunoglobulin G4, with measurement of serum levels of the latter. Management of the condition is medical, with corticosteroids and immunosuppression, rather than surgical excision.

Autoimmune pancreatitis and IgG4-related systemic diseases

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis that is characterized by lymphoplasmacytic infiltrate, storiform fibrosis, obliterative phlebitis, and increased IgG4(+) plasma cells. Serum IgG4 levels usually are elevated. Patients with AIP frequently have disease affecting other organs or sites; these tissues show similar histologic changes, including increased IgG4(+) plasma cell infiltrate and response to corticosteroid therapy. A new clinicopathologic concept of IgG4-related systemic disease (ISD) has been proposed. These diseases often are not limited to the pancreas, and the pancreas may not be involved at all. In this article, we review the literature and our own experience to detail the clinicopathologic features of AIP and extrapancreatic lesions in ISD.

[Sclerosing mesenteritis: can it be a IgG4 dysimmune disease?]

AIMS

Mesenteric panniculitis (MP), sclerotic mesenteritis (SM) and mesenteric lipodystrophy (ML) are the three histopathological forms of a rare inflammatory mesenteric disease. The pathogenesis is unknown until now. Hypothesis of a dysimmune disorder is advocated. Our purpose was to find histological basis to assert this hypothesis.

MATERIAL AND METHODS

All patients with a diagnosis of inflammatory mesenteric disease made in Beaujon hospital were selected. A histological study and a systematic immunostaining with IgG4, CD3 and CD8 antibodies were performed for each patient with paraffin block available. Dysimmune features were defined by: a plasma cells component >30 %, an eosinophilic polynuclears component >10 %, a rate TCD8/CD3 >30 % and IgG4+ plasma cells >30/high power field (x400). Cases were classified in 3 forms on the basis of the predominant component: MP (lymphoid/plasma cell infiltrate), SM (fibrosis), ML (fat necrosis).

RESULTS

Thirteen patients (7 men, 6 women) were selected, with a mean age of 57 years (21-80 years); a paraffin block was available for 10 patients. The clinical and histological presentations were heterogeneous: a mesenteric mass was the most frequent mode of revelation (6/13 patients) and all histological forms were present (3 MP, 5 SM and 5 ML). Nine patients had surgical biopsy, 2 had a trephine biopsy and 2 a resection. Standard histological analysis showed numerous eosinophils (> or =10 %) and plasma cells (>30 %) in respectively 3 (23 %) and 6 (46 %) of the 13 cases. The immunohistochemistry (performed in 10 patients) showed numerous TCD8+ in 80 % of the cases and numerous IgG4+ plasma cells in only 31 % of the cases (4 cases) (IgG4+ >30/x400).

CONCLUSIONS

Our results demonstrate that inflammatory mesenteric diseases are heterogeneous: high components of plasma cells, eosinophils and TCD8+ lymphocytes were found respectively in 46, 23 and 80 % of cases; eosinophils were observed exclusively in sclerotic forms. Only 31 % of cases encompass numerous IgG4+ plasma cells, suggesting a pathogenesis different than hyper-IgG4 diseases.

Distinct clinical, serological, and sonographic characteristics of hashimoto's thyroiditis based with and without IgG4-positive plasma cells

CONTEXT

IgG4-related sclerosing disease is a new syndrome characterized by high serum IgG4 levels and increased IgG4-positive plasma cells in the involved organs. Recently the first description was made by our group of a subsection of Hashimoto's autoimmune thyroiditis (HT) patients showing indistinguishable histopathological features with IgG4-related sclerosing disease, which was termed as IgG4 thyroiditis.

OBJECTIVE

The objective of the study was analysis of the immunophenotypic features of IgG4 in 70 cases of HT patients and to clarify the histopathological and clinical characteristics of the patients with IgG4 thyroiditis.

DESIGN

Thyroid tissue samples were obtained from 70 patients with HT who were treated surgically. Quantitative analyses of the expression of IgG4 and IgG were performed. Statistical analyses of clinical and histopathological parameters were also conducted.

RESULTS

On the basis of immunohistochemistry of IgG4 and IgG4/IgG ratio, the 70 patients with HT were divided into two groups: IgG4 thyroiditis (19 cases) and non-IgG4 thyroiditis (51 cases). Histopathologically, IgG4 thyroiditis showed higher grade of stromal fibrosis, lymphoplasmacytic infiltration, and follicular cell degeneration than non-IgG4 thyroiditis. Moreover, these two groups were also demonstrated to be related with different clinical features, with IgG4 thyroiditis associated more with male gender, rapid progress, subclinical hypothyroidism, more diffuse low echogenicity, and higher level of circulating antibodies.

CONCLUSIONS

From both clinical and histopathological aspects, IgG4 thyroiditis and non-IgG4 thyroiditis were demonstrated to be distinct entities. Measuring serum IgG4 concentration provides a useful method of distinguishing IgG4 thyroiditis from non-IgG4 thyroiditis.

A case of incidentally detected IgG4-related sclerosing disease involving inflammatory abdominal aortic aneurysm and autoimmune pancreatitis

A 59-year-old asymptomatic man was incidentally found to have a periaortic mass and an elevated serum amylase level during his medical check-up. Additional findings, such as infiltration of immunoglobulin G4 (IgG4)-producing plasma cells in the mass lesion, elevation of serum IgG4 (1000 mg/dl), and pancreatic duct narrowing as evidenced on a magnetic resonance cholangiopancreatography scan, confirmed the diagnosis as retroperitoneal fibrosis complicated with autoimmune pancreatitis. The patient responded favorably to steroid treatment before the appearance of symptoms.

IgG4-related sclerosing mastitis: description of a new member of the IgG4-related sclerosing diseases

Immunoglobulin G (IgG)4-related sclerosing disease is a recently described syndrome characterized by mass-forming lesions in various organs due to dense lymphoplasmacytic infiltrates and stromal sclerosis, elevated serum IgG4 titer, increased tissue IgG4 plasma cells, and favorable clinical outcome. We describe 4 patients with IgG4-related sclerosing mastitis, which represents a new member of this family of diseases. All patients were female with a mean age of 47.5 years, presenting with painless masses in 1 or both breasts. One patient had concurrent IgG4-related lymphadenopathy, and another had eyelid swelling of undetermined cause. The serum IgG4 titer was elevated in 1 tested patient, and circulating autoantibodies were found in 3 tested patients. All patients were well with no recurrence after excision or biopsy of the mass. Histologically, the breast masses featured dense lymphoplasmacytic infiltrates, prominent stromal sclerosis and loss of breast lobules. Phlebitis was present in 1 case. IgG4 cells ranged from 272 to 495 per high-power field, constituting 49% to 85% of all IgG cells. IgG4 cells were scarce in 9 of 9 cases of lymphocytic mastitis and 6 of 7 cases of granulomatous mastitis studied as controls. In summary, IgG4-related sclerosing mastitis appears to be a distinctive form of mastitis, sometimes accompanied by other components of IgG4-related sclerosing disease, and shows a favorable clinical outcome.

IgG4-related lung disease in a worker occupationally exposed to asbestos

A case of IgG4-related lung disease in a worker who had been exposed to asbestos is described. The patient had nocturnal cough and wheeze that responded to inhaled corticosteroid, and the radioallergosorbent test was positive against common allergens, suggesting an association with atopic asthma. IgE elevation is reported in asbestos-exposed workers, and asbestos exposure may cause atopic conditions. Predominance of Th2 cytokines and up-regulation of regulatory T lymphocytes have been reported in IgG4-related disease. IgG4-related disease may occur from hypersensitivity of the regulatory immune system to atopic conditions. Asbestos exposure may be a causal factor of IgG4-related disease.

Immunohistochemistry of IgG4 can help subclassify Hashimoto's autoimmune thyroiditis

IgG4-related sclerosing disease has been recently recognized as a systemic disease entity characterized by an elevated serum IgG4 level, sclerosing fibrosis and diffuse lymphoplasmacytic infiltration by many IgG4-positive plasma cells. Similar histopathological features have often been noted in the fibrous variant of Hashimoto's autoimmune thyroiditis, but thyroid gland involvement has been only briefly mentioned with regard to IgG4, and no immunohistochemistry for IgG4 has been reported in Hashimoto's autoimmune thyroiditis. Herein, the purpose of the present study was to investigate the infiltration of IgG- and IgG4-positive plasma cells on immunohistochemistry for a panel of thyroiditis samples (Hashimoto's autoimmune thyroiditis, n= 13; subacute thyroiditis, n= 2; lymphocytic thyroiditis, n= 2). Cases of Hashimoto's thyroiditis could be classified into two groups based on immunostaining of IgG4: IgG4 thyroiditis (IgG4-related, IgG4-positive plasma cell-rich thyroiditis) and non-IgG4 thyroiditis (non-IgG4-related, IgG4-positive plasma cell-poor thyroiditis). IgG4 thyroiditis presents with severe lymphoplasmacytic infiltration, dense fibrosis, marked follicular cell degeneration, oxyphilic change and lymphoid follicle formation, while non-IgG4 thyroiditis presents with relatively mild or absent histopathological characteristics. In conclusion, immunostaining of IgG4 can help subclassify Hashimoto's thyroiditis; and IgG4 thyroiditis may have a close relationship with IgG4-related sclerosing disease.

A case of IgG4-related sclerosing disease with retroperitoneal fibrosis, autoimmune pancreatitis and bilateral focal nephritis

A 74-year-old male patient presented with progressive anorexia, cholestatic liver function tests, and a diffuse enlarged pancreas suggestive of a pancreatic carcinoma. There was a marked elevation of total immunoglobulin G4 (IgG4) in serum. Further investigation led to the diagnosis of IgG4-related sclerosing disease with involvement of the pancreas, retroperitoneal fibrosis, and bilateral focal nephritis. To our knowledge, this is the first report on these 3 clinical entities occurring in the same patient.A short review of the literature concerning autoimmune pancreatitis and retroperitoneal fibrosis is made, with special interest to the concept of IgG4-related pathology. This systemic disease can have several clinical manifestations: IgG4-positivity not only can be found in the pancreas, but also at the level of extrahepatic biliary ducts, gallbladder, salivary glands, retroperitoneal tissue, kidneys, ureters, and lymph nodes. Although further investigation is required to determine its exact pathophysiologic role, IgG4 seems to be an important key player.

[Is hypertrophic pachymeningitis a dural lesion of IgG4-related systemic disease?]

Both multifocal fibrosclerosis and hypertrophic pachymeningitis are rare disorders of unknown etiology, characterised by chronic inflammation leading to dense fibrosis. There have been several reports of multifocal fibrosclerosis with hypertrophic pachymeningitis. Autoimmune pancreatitis is frequently associated with various extrapancreatic lesions, their pathological similarities such as dense inflammatory fibrosis with lymphoplasmacytic infiltration strongly suggests a close relationship between autoimmune pancreatitis and multifocal fibrosclerosis. Recently, autoimmune pancreatitis including these systemic fibrosing disorders may be classified as IgG4-related systemic disease. However, the relationship between HP and IgG4-related systemic disease is still uncertain. We performed immunohistochemical examinations in autopsy specimens from a patients with HP. Histological findings can be summarized as follows: sever interstitial fibrosis and diffuse inflammatory cells infiltration, presenting nonspecific inflammatory changes. Immunohistochemically, diffuse infiltrates in the dura consisted predominantly of UCHL-1 positive T or L-26 positive B lymphocytes. Many IgG4 positive plasma cells were also infiltrated. To our knowledge, this may be the first report which showed IgG4 positive plasma cells infiltration in the dura in a patient with HP. It is postulated that HP may be a dural lesion of IgG4-related systemic disease.

Idiopathic fibroinflammatory disease of the face, eyelids, and periorbital membrane with immunoglobulin G4-positive plasma cells

Progressive sclerosing orbital pseudotumors are a subset of usually primary and localized idiopathic fibroinflammatory disorders. We report on a 66-year-old man who developed this condition along the facial tissue planes with extension into the orbit and preferential involvement of the periorbital membrane. Fibrocollagenous tissue with scattered lymphoid aggregates without follicle formation dominated the process. There was a light dispersion of B and T lymphocytes and histiocytes in the stroma. Immunoglobulin G4 (IgG4)-positive plasma cells (>35 per high-power field) were identified mostly in the lymphoid clusters, as has been discovered in similar IgG4-related fibrosclerosing conditions of other nonorbital sites. No associated systemic disease emerged during a 20-year clinical course. Previously reported orbital cases of IgG4-positive disease have all involved the lacrimal gland, usually bilaterally, and more closely resembled hypercellular reactive lymphoid hyperplasias with moderate interlobular fibrosis, rather than representing an essentially sclerosing process from the beginning.

A case of IgG4-related sclerosing disease complicated by sclerosing cholangitis, retroperitoneal fibrosis and orbital pseudotumour

We present a case of IgG4-related sclerosing disease complicated by sclerosing cholangitis (SC), idiopathic retroperitoneal fibrosis (IRF) and orbital pseudotumour (OPT). Clinical, radiographic and pathological findings later suggested that the patient had SC complicated by IRF. The patient's SC and IRF were well controlled for the first 10 years of the follow-up period; OPT developed in the tenth year. During investigation of the OPT, serum IgG4 level was found to be significantly elevated. The patient was then diagnosed with IgG4-related sclerosing disease complicated by SC, IRF and OPT. This is a rare manifestation of IgG4-related sclerosing disease, which was diagnosed incidentally during OPT work-up. We suggest that this is a variation of the so-called IgG4-related sclerosing disease or hyper-IgG4 disease.

[Autoimmune pancreatitis]

Autoimmune pancreatitis has been established as a special entity of pancreatitis. It is an enigmatic disease since it is adding an autoimmune etiology to the existing causes of pancreatitis. Morphological hallmarks of the disease are narrowing of the pancreatic duct system and the bile duct by periductal lymphoplasmocytic inflammation. This results in many cases in obstructive jaundice due to a mass-forming lesion in the pancreatic head mimicking pancreatic ductal adenocarcinoma. Therefore, patients will frequently undergo surgery. Histopathologically, the disease can be diagnosed by IgG4-positive plasma cells. Serologically, patients may present with elevated serum IgG and IgG4 levels. Other autoantibodies are also described. Association with other autoimmune manifestations in a wide range of organs is frequent. Autoimmune pancreatitis will respond to steroid treatment, which is of specific importance because pancreatic cancer is one of its clinical differential diagnoses. It is important to positively diagnose autoimmune pancreatitis, especially if the bile ducts are affected, since cholangitis may be or become a prominent problem before or after surgery.

Immunoglobulin G4: an odd antibody

Despite its well-known association with IgE-mediated allergy, IgG4 antibodies still have several poorly understood characteristics. IgG4 is a very dynamic antibody: the antibody is involved in a continuous process of half-molecules (i.e. a heavy and attached light-chain) exchange. This process, also referred to as 'Fab-arm exchange', results usually in asymmetric antibodies with two different antigen-combining sites. While these antibodies are hetero- bivalent, they will behave as monovalent antibodies in most situations. Another aspect of IgG4, still poorly understood, is its tendency to mimic IgG rheumatoid factor (RF) activity by interacting with IgG on a solid support. In contrast to conventional RF, which binds via its variable domains, the activity of IgG4 is located in its constant domains. This is potentially a source of false positives in IgG4 antibody assay results. Because regulation of IgG4 production is dependent on help by T-helper type 2 (Th2) cells, the IgG4 response is largely restricted to non-microbial antigens. This Th2-dependency associates the IgG4 and IgE responses. Another typical feature in the immune regulation of IgG4 is its tendency to appear only after prolonged immunization. In the context of IgE-mediated allergy, the appearance of IgG4 antibodies is usually associated with a decrease in symptoms. This is likely to be due, at least in part, to an allergen-blocking effect at the mast cell level and/or at the level of the antigen-presenting cell (preventing IgE-facilitated activation of T cells). In addition, the favourable association reflects the enhanced production of IL-10 and other anti-inflammatory cytokines, which drive the production of IgG4. While in general, IgG4 is being associated with non-activating characteristics, in some situations IgG4 antibodies have an association with pathology. Two striking examples are pemphigoid diseases and sclerosing diseases such as autoimmune pancreatitis. The mechanistic basis for the association of IgG4 with these diseases is still enigmatic. However, the association with sclerosing diseases may reflect an excessive production of anti-inflammatory cytokines triggering an overwhelming expansion of IgG4-producing plasma cells. The bottom line for allergy diagnosis: IgG4 by itself is unlikely to be a cause of allergic symptoms. In general, the presence of allergen-specific IgG4 indicates that anti-inflammatory, tolerance-inducing mechanisms have been activated. The existence of the IgG4 subclass, its up-regulation by anti-inflammatory factors and its own anti-inflammatory characteristics may help the immune system to dampen inappropriate inflammatory reactions.

Salivary duct carcinoma arising in IgG4-related autoimmune disease of the parotid gland

Hyper IgG4 disease or IgG4-related sclerosing/autoimmune disease is a multisystem condition characterized histologically by fibrosis, lymphoplasmacytic infiltration, and abundant IgG4 plasma cells associated with raised serum IgG4 levels. We present a case of salivary duct carcinoma of the parotid gland in a background of chronic sclerosing sialadenitis that also involved the submandibular gland with associated regional lymphadenopathy. The serology showed raised total IgG levels of 16.3 g/L (reference range, 6.0-15.0) and raised IgG4 levels of 3.41 g/L (reference range, 0.07-1.70). The salivary duct carcinoma contained areas of dense fibrosis and abundant IgG4-positive plasma cells (>100 per high-power field [hpf]). The adjacent noncarcinomatous areas, submandibular gland, and regional lymph nodes also contained plasma cells immunoreactive to IgG4 with densities higher than 100/hpf. To the best of our knowledge, this case is the first documentation of malignancy occurring in a background of IgG4-related autoimmune disease of the salivary gland.