BackgroundThe aim was to further characterize immunoglobulin G4-related disease (IgG4-RD) by a large-scale multicenter study of its clinical and laboratory features conducted by multidisciplinary physicians of IgG4-RD in Japan.MethodsVarious specialists retrospectively evaluated IgG4-RD patients diagnosed between 1996 and 2015 in five hospitals by analyzing their baseline clinical features, laboratory, imaging, and pathological test findings, and treatment.ResultsOf the 334 patients listed, 205 were male and median age at diagnosis was 65 years. The mean number of organs involved was 3.2 at diagnosis. The most frequently affected organs were the salivary glands, followed by the lacrimal glands, lymph nodes, pancreas, retroperitoneum/periaorta, kidneys, and lungs. The mean serum level of IgG4 was 755 mg/dl, and more than 95% of patients had elevated serum IgG4 levels. The median serum level of C-reactive protein (CRP) was 0.1 mg/dl and the level was less than 1 mg/dl in 90% of patients. A total of 34.7% of patients had low serum levels of C3. Serum levels of C3 and non-IgG4 IgG, calculated as the total IgG minus IgG4, showed an inverse correlation in patients with kidney lesions, while serum IgG4 levels were not correlated with serum C3 levels. Corticosteroid was administered in 78.0% of patients, and was effective in all.ConclusionsThe serum CRP level is generally low and the serum IgG4 level is elevated in most Japanese IgG4-RD patients, in contrast to western patients. These original findings suggest that these two parameters in IgG4-RD differ in some interesting ways from those hitherto reported in western populations. Additional studies, especially international comparative ones, are needed to elucidate the extent and significance of these differences between populations. Attention will also have to be paid to whether the existence of such differences requires consideration when devising international classification criteria.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-017-1467-x) contains supplementary material, which is available to authorized users.

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Objectives In IgG4-related disease (IgG4-RD), relapse including recurrent organ involvement (ROI) and de novo organ involvement (DNOI) occurs frequently during the clinical course. This study aimed to clarify the differences between the risk factors underlying ROI and DNOI in IgG4-RD. Methods We retrospectively investigated factors related to ROI and DNOI in 86 IgG4-RD patients. For assessment of factors related to ROI and DNOI, we performed uni- and multivariate Cox regression analyses. On stepwise multivariate analysis, we applied the variables with P < 0.1 in the univariate analysis and the predictors of relapse suggested in past reports. Results During the mean follow-up period of 63.1 months, ROI was detected at 1.0–120 months after diagnosis in 20 patients, 4 of whom were not receiving glucocorticoid (GC) at the time of ROI. In contrast, DNOI was detected at 5.0–120 months after diagnosis in 15 patients, 8 of whom were not receiving GC at the time of DNOI. In the multivariate analysis, blood eosinophil counts at diagnosis [per 100/μl; hazard ratio (HR) 1.072 (95% CI 1.018, 1.129)] and continuation of GC [vs discontinuation or observation without GC; HR 0.245 (95% CI 0.076, 0.793)] had a significant impact on the time to DNOI, whereas age [HR 0.942 (95% CI 0.899, 0.986)] and ANA positivity [vs negativity; HR 6.632 (95% CI 1.892, 23.255)] had a significant impact on the time to ROI. Conclusion The present study suggests that the risk factors of ROI and DNOI are different in IgG4-RD, highlighting the need for different preventative strategies.

We describe an 81-year-old man with immunoglobulin G4-related disease (IgG4-RD) presenting with submandibular gland, lymph node, lung, kidney, aortic wall, and prostate lesions with concomitant gastric cancer. After curative surgical treatment of the gastric cancer, corticosteroid therapy for progressively decreasing renal function was started. Before starting steroid therapy, fluorodeoxyglucose positron emission tomography-computed tomography revealed multiple lesions of IgG4-RD but no metastasis of the cancer. However, the patient died 3 months after initiation of corticosteroid therapy because of recurrence of the gastric cancer. In this case, the imaging features of IgG4-tubulointerstitial nephritis dramatically changed during the clinical course of co-existing gastric cancer. The imaging features of the present case may provide clues to the pattern of spread of IgG4 lesions in the kidney.