IgG4-related disease (IgG4-RD) is considered a systemic, chronic, and inflammatory disorder that is characterized by the enlargement of involved organs, elevated levels of IgG4, and abundant infiltration of plasmacytes with IgG4 and fibrosis in involved organs. It is necessary to differentiate IgG4-RD from malignant tumors. Recently we have looked at case reports of IgG4-RD with malignancy that was discovered at systemic screening. In this study, we analyzed the relationship between IgG4-RD and malignancies. The study subjects were 106 patients with IgG4-RD who had been referred to our hospital since April 1997. We analyzed the clinical characteristics of IgG4-RD patients who had cancer that was observed upon the initial diagnosis of IgG4-RD or that occurred during an average follow-up period of 3.1 years. Using data from national cancer registries that monitor cancer incidence in Japan, we evaluated the standardized incidence ratio (SIR) for malignancies in IgG4-RD. Malignancies were observed in 11 of the IgG4-RD patients (10.4%). The malignancies were all different and included lung cancer, colon cancer, and lymphoma. With the exception of the age at which the IgG4-RD diagnosis was made, there were no common features in patients with cancer and those without. The SIR for these malignancies in IgG4-RD was 383.0, which was higher than that for the general population. We should be cognizant of the possible existence of malignancies in patients with IgG4-RD at the time of diagnosis and during follow-up care.

IgG4-related disease (IgG4-RD) is considered a systemic, chronic, and inflammatory disorder that is characterized by the enlargement of involved organs, elevated levels of IgG4, and abundant infiltration of plasmacytes with IgG4 and fibrosis in involved organs. It is necessary to differentiate IgG4-RD from malignant tumors. Recently we have looked at case reports of IgG4-RD with malignancy that was discovered at systemic screening. In this study, we analyzed the relationship between IgG4-RD and malignancies. The study subjects were 106 patients with IgG4-RD who had been referred to our hospital since April 1997. We analyzed the clinical characteristics of IgG4-RD patients who had cancer that was observed upon the initial diagnosis of IgG4-RD or that occurred during an average follow-up period of 3.1 years. Using data from national cancer registries that monitor cancer incidence in Japan, we evaluated the standardized incidence ratio (SIR) for malignancies in IgG4-RD. Malignancies were observed in 11 of the IgG4-RD patients (10.4%). The malignancies were all different and included lung cancer, colon cancer, and lymphoma. With the exception of the age at which the IgG4-RD diagnosis was made, there were no common features in patients with cancer and those without. The SIR for these malignancies in IgG4-RD was 383.0, which was higher than that for the general population. We should be cognizant of the possible existence of malignancies in patients with IgG4-RD at the time of diagnosis and during follow-up care.

Objective. Immunoglobulin (Ig)G4-related disease (IgG4-RD) is a new disease entity that has only been identified this century. Clinical information is thus lacking. We established the Sapporo Medical University and Related Institutes Database for Investigation and Best Treatments of IgG4-related Disease (SMART) to clarify the clinical features of IgG4-RD and provide useful information for clinicians. Methods. Participants comprised 122 patients with IgG4-related dacryoadenitis and/or sialadenitis (IgG4-DS), representing lacrimal and/or salivary lesions of IgG4-RD, followed-up in December 2013. We analyzed the sex ratio, mean age at onset, organ dysfunction, history or complications of malignancy, treatments, rate of clinical remission, and relapse. Results. The sex ratio was roughly equal. Mean age at diagnosis was 59.0 years. Positron emission tomography revealed that the ratio of other organ involvements was 61.4%. Complications of malignancy were observed in 7.4% of cases. Glucocorticoid was used to treat 92.1% of cases, and the mean maintenance dose of prednisolone was 4.8 mg/day. Rituximab was added in three cases, and showed good steroid-sparing effect. The clinical remission rate was 73.8%, and the annual relapse rate was 11.5%. Half of the cases experienced relapses within 7 years of initial treatment. Conclusion. We analyzed the clinical features and treatments of IgG4-DS using SMART, providing useful information for everyday clinical practice.

IgG4-related disease (IgG4-RD) is a novel disease entity that includes Mikulicz's disease, autoimmune pancreatitis (AIP), and many other conditions. It is characterized by elevated serum IgG4 levels and abundant IgG4-bearing plasmacyte infiltration of involved organs. We postulated that high levels of serum IgG4 would comprise a useful diagnostic tool, but little information is available about IgG4 in conditions other than IgG4-RD, including rheumatic diseases. Several reports have described cutoff values for serum IgG4 when diagnosing IgG4-RD, but these studies mostly used 135 mg/dL in AIP to differentiate from pancreatic cancer instead of rheumatic and other common diseases. There is no evidence for a cutoff serum IgG4 level of 135 mg/dL for rheumatic diseases and common diseases that are often complicated with rheumatic diseases. The aim of this work was to re-evaluate the usual cutoff serum IgG4 value in AIP (135 mg/dL) that is used to diagnose whole IgG4-RD in the setting of a rheumatic clinic by measuring serum IgG4 levels in IgG4-RD and various disorders. We therefore constructed ROC curves of serum IgG4 levels in 418 patients who attended Sapporo Medical University Hospital due to IgG4-RD and various rheumatic and common disorders. The optimal cut-off value of serum IgG4 for a diagnosis of IgG4-RD was 144 mg/dL, and the sensitivity and specificity were 95.10 and 90.76%, respectively. Levels of serum IgG4 were elevated in IgG4-RD, Churg-Strauss syndrome, multicentric Castleman's disease, eosinophilic disorders, and in some patients with rheumatoid arthritis, systemic sclerosis, chronic hepatitis, and liver cirrhosis. The usual cut-off value of 135 mg/dL in AIP is useful for diagnosing whole IgG4-RD, but high levels of serum IgG4 are sometimes observed in not only IgG4-RD but also other rheumatic and common diseases.

Salivary secretion can be improved even in cases with lower levels of salivary secretion before treatment in IgG4-RD, but improvements in the amount of salivary secretion decrease with histological changes with delayed therapeutic intervention. These data suggest that early intervention is needed to improve outcomes in patients with IgG4-MD.

IgG4-related disease (IgG4-RD) is a novel disease entity that includes Mikulicz's disease, autoimmune pancreatitis (AIP), and many other conditions. It is characterized by elevated serum IgG4 levels and abundant IgG4-bearing plasmacyte infiltration of involved organs. We postulated that high levels of serum IgG4 would comprise a useful diagnostic tool, but little information is available about IgG4 in conditions other than IgG4-RD, including rheumatic diseases. Several reports have described cutoff values for serum IgG4 when diagnosing IgG4-RD, but these studies mostly used 135 mg/dL in AIP to differentiate from pancreatic cancer instead of rheumatic and other common diseases. There is no evidence for a cutoff serum IgG4 level of 135 mg/dL for rheumatic diseases and common diseases that are often complicated with rheumatic diseases. The aim of this work was to re-evaluate the usual cutoff serum IgG4 value in AIP (135 mg/dL) that is used to diagnose whole IgG4-RD in the setting of a rheumatic clinic by measuring serum IgG4 levels in IgG4-RD and various disorders. We therefore constructed ROC curves of serum IgG4 levels in 418 patients who attended Sapporo Medical University Hospital due to IgG4-RD and various rheumatic and common disorders. The optimal cut-off value of serum IgG4 for a diagnosis of IgG4-RD was 144 mg/dL, and the sensitivity and specificity were 95.10 and 90.76%, respectively. Levels of serum IgG4 were elevated in IgG4-RD, Churg-Strauss syndrome, multicentric Castleman's disease, eosinophilic disorders, and in some patients with rheumatoid arthritis, systemic sclerosis, chronic hepatitis, and liver cirrhosis. The usual cut-off value of 135 mg/dL in AIP is useful for diagnosing whole IgG4-RD, but high levels of serum IgG4 are sometimes observed in not only IgG4-RD but also other rheumatic and common diseases.

Follow-up is important in cases with recognized risk factors for relapse, including male sex and younger onset in cases without organ damage.

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