Yasufumi Masaki

Consensus statement on the pathology of IgG4-related disease.

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

Proposal for a new clinical entity, IgG4-positive multiorgan lymphoproliferative syndrome: analysis of 64 cases of IgG4-related disorders

Background: Mikulicz’s disease (MD) has been considered as one manifestation of Sjögren’s syndrome (SS). Recently, it has also been considered as an IgG4-related disorder. Objective: To determine the differences between IgG4-related disorders including MD and SS. Methods: A study was undertaken to investigate patients with MD and IgG4-related disorders registered in Japan and to set up provisional criteria for the new clinical entity IgG4-positive multiorgan lymphoproliferative syndrome (IgG4+MOLPS). The preliminary diagnostic criteria include raised serum levels of IgG4 (>135 mg/dl) and infiltration of IgG4+ plasma cells in the tissue (IgG4+/IgG+ plasma cells >50%) with fibrosis or sclerosis. The clinical features, laboratory data and pathologies of 64 patients with IgG4+MOLPS and 31 patients with typical SS were compared. Results: The incidence of xerostomia, xerophthalmia and arthralgia, rheumatoid factor and antinuclear, antiSS-A/Ro and antiSS-B/La antibodies was significantly lower in patients with IgG4+MOLPS than in those with typical SS. Allergic rhinitis and autoimmune pancreatitis were significantly more frequent and total IgG, IgG2, IgG4 and IgE levels were significantly increased in IgG4+MOLPS. Histological specimens from patients with IgG4+MOLPS revealed marked IgG4+ plasma cell infiltration. Many patients with IgG4+MOLPS had lymphocytic follicle formation, but lymphoepithelial lesions were rare. Few IgG4+ cells were seen in the tissue of patients with typical SS. Thirty-eight patients with IgG4+MOLPS treated with glucocorticoids showed marked clinical improvement. Conclusion: Despite similarities in the involved organs, there are considerable clinical and pathological differences between IgG4+MOLPS and SS. Based on the clinical features and good response to glucocorticoids, we propose a new clinical entity: IgG4+MOLPS.

A novel clinical entity, IgG4-related disease (IgG4RD): general concept and details

IgG4-related disease (IgG4RD) is a novel clinical disease entity characterized by elevated serum IgG4 concentration and tumefaction or tissue infiltration by IgG4-positive plasma cells. IgG4RD may be present in a certain proportion of patients with a wide variety of diseases, including Mikulicz’s disease, autoimmune pancreatitis, hypophysitis, Riedel thyroiditis, interstitial pneumonitis, interstitial nephritis, prostatitis, lymphadenopathy, retroperitoneal fibrosis, inflammatory aortic aneurysm, and inflammatory pseudotumor. Although IgG4RD forms a distinct, clinically independent disease category and is attracting strong attention as a new clinical entity, many questions and problems still remain to be elucidated, including its pathogenesis, the establishment of diagnostic criteria, and the role of IgG4. Here we describe the concept of IgG4RD and up-to-date information on this emerging disease entity.

Recommendations for the nomenclature of IgG4-related disease and its individual organ system manifestations

John H. Stone, Arezou Khosroshahi, Vikram Deshpande, John K. C. Chan, J. Godfrey Heathcote, Rob Aalberse, Atsushi Azumi, Donald B. Bloch, William R. Brugge, Mollie N. Carruthers, Wah Cheuk, Lynn Cornell, Carlos Fernandez-Del Castillo, Judith A. Ferry, David Forcione, Gunter Kloppel, Daniel L. Hamilos, Terumi Kamisawa, Satomi Kasashima, Shigeyuki Kawa, Mitsuhiro Kawano, Yasufumi Masaki, Kenji Notohara, Kazuichi Okazaki, Ji Kon Ryu, Takako Saeki, Dushyant Sahani, Yasuharu Sato, Thomas Smyrk, James R. Stone, Masayuki Takahira, Hisanori Umehara, George Webster, Motohisa Yamamoto, Eunhee Yi, Tadashi Yoshino, Giuseppe Zamboni, Yoh Zen, and Suresh Chari

International consensus guidance statement on the management and treatment of IgG4-related disease

A. Khosroshahi, Z. S. Wallace, J. L. Crowe, T. Akamizu, A. Azumi, M. N. Carruthers, S. T. Chari, E. Della-Torre, L. Frulloni, H. Goto, P. A. Hart, T. Kamisawa, S. Kawa, M. Kawano, M. H. Kim, Y. Kodama, K. Kubota, M. M. Lerch, M. L€ ohr, Y. Masaki, S. Matsui, T. Mimori, S. Nakamura, T. Nakazawa, H. Ohara, K. Okazaki, J. H. Ryu, T. Saeki, N. Schleinitz, A. Shimatsu, T. Shimosegawa, H. Takahashi, M. Takahira, A. Tanaka, M. Topazian, H. Umehara, G. J. Webster, T. E. Witzig, M. Yamamoto, W. Zhang, T. Chiba, and J. H. Stone

IgG4‐related disease: Historical overview and pathology of hematological disorders

IgG4‐related diseases comprise a recently recognized systemic syndrome characterized by mass‐forming lesions in mainly exocrine tissue that consist of lymphoplasmacytic infiltrates and sclerosis. There are numerous IgG4‐positive plasma cells in the affected tissues, and the serum IgG4 level is increased in these patients. The present study describes the history, autoimmune pancreatitis (AIP), IgG4‐related lymphadenopathy and lymphomagenesis based upon ocular adnexal IgG4‐related disease. Lymphoplasmacytic sclerosing pancreatitis, a prototypal histological type of AIP, is now recognized as a systemic IgG4‐related disease. Lymph node lesions can be subdivided into at least five histological subtypes, and systemic IgG4‐related lymphadenopathy should be distinguished from multicentric Castlemans disease. Interleukin‐6 and CRP levels are abnormally high in multicentric Castlemans disease, but are normal in the majority of systemic IgG4‐related lymphadenopathy. Ocular adnexal IgG4‐related disease frequently involves bilateral lacrimal glands swelling, and obliterative phlebitis is rare. Moreover, some malignant lymphomas, especially mucosa‐associated lymphoid tissue lymphoma, arise from ocular adnexal IgG4‐related disease. In addition, IgG4‐producing lymphoma also exists.

IgG4-related Diseases Including Mikulicz’s Disease and Sclerosing Pancreatitis: Diagnostic Insights

Since the first report of serum IgG4 elevation in sclerosing pancreatitis in 2001, various systemic disorders have been reported to elevate IgG4, and many names have been proposed from the perspective of the systemic condition. Despite similarities in the organs damaged in IgG4-related Mikulicz’s disease and Sjögren’s syndrome, there are marked clinical and pathological differences between the 2 entities. The majority of cases diagnosed with autoimmune pancreatitis in Japan are IgG4-related sclerosing pancreatitis, and it should be recognized that this is distinct from the Western type. Diagnosis of IgG4-related disease is defined by both elevated serum IgG4 (> 1.35 g/l) and histopathological features, including lymphocyte and IgG4+ plasma cell infiltration (IgG4+ plasma cells/IgG+ plasma cells > 50% on a highly magnified slide checked at 5 points). Differential diagnosis from other distinct disorders is necessary: these include sarcoidosis, Castleman’s disease, Wegener’s granulomatosis, lymphoma, cancer, and other existing conditions. The Japanese IgG4 research group has begun multicenter prospective studies to improve diagnostic criteria and treatment strategies.

Retrospective Analysis of Intravascular Large B-Cell Lymphoma Treated With Rituximab-Containing Chemotherapy As Reported by the IVL Study Group in Japan

PURPOSE To evaluate the safety and efficacy of rituximab-containing chemotherapies for intravascular large B-cell lymphoma (IVLBCL). PATIENTS AND METHODS We retrospectively analyzed 106 patients (59 men, 47 women) with IVLBCL who received chemotherapy either with rituximab (R-chemotherapy, n = 49) or without rituximab (chemotherapy, n = 57) between 1994 and 2007 in Japan. The median patient age was 67 years (range, 34 to 84 years). The International Prognostic Index was high-intermediate/high in 97% of patients. RESULTS The complete response rate was higher for patients in the R-chemotherapy group (82%) than for those in the chemotherapy group (51%; P = .001). The median duration of follow-up for surviving patients was 18 months (range, 1 to 95 months). Progression-free survival (PFS) and overall survival (OS) rates at 2 years after diagnosis were significantly higher for patients in the R-chemotherapy group (PFS, 56%; OS, 66%) than for patients in the chemotherapy group (PFS, 27% with P = .001; OS, 46% with P = 0.01). Multivariate analysis revealed that the use of rituximab was favorably associated with PFS (hazard ratio [HR], 0.45; 95% CI, 0.25 to 0.80; P = .006) and OS (HR, 0.42; 95% CI, 0.21 to 0.85; P = .016). Treatment-related death was observed in three patients (6%) who received R-chemotherapy and in five patients (9%) who received chemotherapy. CONCLUSION Our data suggest improved clinical outcomes for patients with IVLBCL in the rituximab era. Future prospective studies of rituximab-containing chemotherapies are warranted.

Lymphoproliferative disorders in Sjögren's syndrome.

Sjögrens syndrome (SS) is a chronic organ-specific autoimmune disease characterized by lymphocytic infiltration into the salivary and lacrimal glands. About half of primary SS patients develop systemic disorders. Primary SS can be divided into three stages according to the extent of organ damage and the course of the disease. In stage I, (approx. 45% of cases), patients have only sicca syndrome and do not experience any systemic involvement, even after 10 years. In stage II (approx. 50% of cases), patients experience lymphocytic organ damage, which may involve the pulmonary, renal, hepatic, hematologic, and/or dermatologic systems, among others. Finally, in stage III (approx. 5% of cases), patients develop malignant lymphomas. Lymphomas in salivary glands are thought to arise from lymphoepithelial lesions in which there are close interactions among epithelial cells, T cells, and B cells. The B cells in the lesions become activated through the interaction between CD40L and CD40. The progression from polyclonal lymphoproliferation to monoclonal lymphoproliferation, to mucosa-associated lymphoid tissue (MALT) lymphoma, and finally to high-grade malignant lymphoma is regarded as a multi-step process. Antigenic activation of B cells, together with oncogenic events, including p53 inactivation and bcl-2 activation, may play important roles in B cell monoclonal proliferation and malignant transformation. The rheumatoid factor clone is regarded as a candidate B cell clone that undergoes transformation.

Cutoff Values of Serum IgG4 and Histopathological IgG4+ Plasma Cells for Diagnosis of Patients with IgG4-Related Disease.

IgG4-related disease is a new disease classification established in Japan in the 21st century. Patients with IgG4-related disease display hyper-IgG4-gammaglobulinemia, massive infiltration of IgG4+ plasma cells into tissue, and good response to glucocorticoids. Since IgG4 overexpression is also observed in other disorders, it is necessary to diagnose IgG4-related disease carefully and correctly. We therefore sought to determine cutoff values for serum IgG4 and IgG4/IgG and for IgG4+/IgG+ plasma cells in tissue diagnostic of IgG4-related disease. Patients and Methods. We retrospectively analyzed serum IgG4 concentrations and IgG4/IgG ratio and IgG4+/IgG+ plasma cell ratio in tissues of 132 patients with IgG4-related disease and 48 patients with other disorders. Result. Serum IgG4 >135  mg/dl demonstrated a sensitivity of 97.0% and a specificity of 79.6% in diagnosing IgG4-related disease, and serum IgG4/IgG ratios >8% had a sensitivity and specificity of 95.5% and 87.5%, respectively. IgG4+cell/IgG+ cell ratio in tissues >40% had a sensitivity and specificity of 94.4% and 85.7%, respectively. However, the number of IgG4+ cells was reduced in severely fibrotic parts of tissues. Conclusion. Although a recent unanimous consensus of all relevant researchers in Japan recently established the diagnostic criteria for IgG4-related disease, findings such as ours indicate that further discussion is needed.