Dai Inoue

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.

Proposal for diagnostic criteria for IgG4-related kidney disease.

BackgroundIgG4-related disease has attracted wide attention recently. It is characterized by a high level of serum IgG4 and dense infiltration of IgG4-positive plasma cells into multiple organs, with the kidney being one representative target. Although several sets of diagnostic criteria for autoimmune pancreatitis (AIP) are available and renal lesion is recognized as an extra-pancreatic manifestation of AIP, it is difficult to differentiate IgG4-related tubulointerstitial nephritis (TIN) without AIP from other types of TIN. To clarify the entity of IgG4-related kidney disease (IgG4-RKD) and support in-depth studies, the Japanese Society of Nephrology has established a working group to prepare diagnostic criteria for IgG4-RKD.MethodThe working group analyzed 41 patients with IgG4-RKD, and collected the following data to devise a diagnostic algorithm and diagnostic criteria for IgG4-RKD: clinical features including extra-renal organ involvement, urinalysis and serological features including serum IgG4 levels, imaging findings demonstrated by computed tomography (CT), renal histology with IgG4 immunostaining, and response to steroid therapy.ResultsThe conditions for criteria are as follows. (1) Presence of some kidney damage, as manifested by abnormal urinalysis or urine marker(s) and/or decreased kidney function with either elevated serum IgG level, hypocomplementemia, or elevated serum IgE level. (2) Kidney imaging studies showing abnormal renal imaging findings, i.e., multiple low density lesions on enhanced CT, diffuse kidney enlargement, hypovascular solitary mass in the kidney, and hypertrophic lesion of the renal pelvic wall without irregularity of the renal pelvic surface. (3) Serum IgG4 level exceeding 135 mg/dl. (4) Renal histology showing two abnormal findings: (a) dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/high power field (HPF) and/or ratio of IgG4-positive plasma cells/IgG positive plasma cells >40%. (b) Characteristic ‘storiform’ fibrosis surrounding nests of lymphocytes and/or plasma cells. (5) Extra-renal histology showing dense lymphoplasmacytic infiltration with infiltrating IgG4-positive plasma cells >10/HPF and/or ratio of IgG4-positive plasma cells/IgG-positive plasma cells >40%. The diagnosis is classified into 3 stages of definite, probable and possible according to the combinations of the above conditions. Thirty-nine cases (95.1%) were diagnosed with IgG4-RKD according to the criteria.ConclusionThe provisional criteria and algorithm appear to be useful for clarifying the entity of IgG4-RKD and seeking underlying IgG4-RKD cases; however, further experience is needed to confirm the validity of these criteria.

IgG4-related lung and pleural disease: a clinicopathologic study of 21 cases.

Immunoglobulin G4 (IgG4)-related disorders can occur in the respiratory system. However, the clinicopathologic characteristics have not been well clarified. In this study, we examined clinical and pathologic features of, and follow-up data on, IgG4-related lung and pleural lesions. The patients group consisted of 17 males and 4 females with an average age of 69 years (range: 42 to 76). Pulmonary lesions in 16 patients and pleural lesions in 5 patients were examined. Histologically, all lesions showed diffuse lymphoplasmacytic infiltration. Irregular fibrosis and obliterative vascular changes were more common in solid areas. Nine cases (43%) had eosinophilic infiltration with more than 5 cells per high-power field. Immunostaining revealed numerous IgG4-positive plasma cells in inflamed areas. Sclerosing inflammation was distributed with intrapulmonary connective tissue. Pulmonary lesions showed a variety of morphologic changes according to the predominant area of inflammation. Serum IgG4 concentrations were elevated in 9 of 11 patients tested (average 6.9 g/L; range 0.3 to 18.0 g/L; normal range <1.35 g/L). Extra-pulmonary and extra-pleural IgG4-related lesions were identified in 9 patients (43%), and developed simultaneously or asynchronously during follow up. All patients treated with steroids responded, but some radiologic abnormalities remained in 3 patients. Interestingly, 1 patient was found to have a primary adenocarcinoma against a background of IgG4-related lung disease during follow up. In conclusion, IgG4-related diseases show a greater variety of pulmonary and pleural lesions than previously thought. It is important, therefore, to know the morphologic variety and clinicopathologic characteristics of this disorder.

Immunoglobulin G4–related Lung Disease: CT Findings with Pathologic Correlations

PURPOSE To retrospectively analyze radiologic findings of immunoglobulin G4 (IgG4)-related lung disease as correlated with pathologic specimens. MATERIALS AND METHODS This study was approved by the institutional review board, and all patients had consented to the use of their medical records for the purpose of research. This study included 13 patients with IgG4-related lung disease (nine men and four women; age range, 43-76 years). Computed tomographic (CT) findings were retrospectively analyzed with regard to the characteristics, shape, and distribution of the radiologic findings and were correlated with surgically resected or biopsy lung specimens in seven patients. Statistical analysis was not used in this study. RESULTS On the basis of the predominant radiologic abnormality, IgG4-related lung disease could be categorized into four major subtypes: solid nodular type having a solitary nodular lesion that included a mass (four patients); round-shaped ground-glass opacity (GGO) type characterized by multiple round-shaped GGOs (two patients); alveolar interstitial type showing honeycombing, bronchiectasis, and diffuse GGO (two patients); and bronchovascular type showing thickening of bronchovascular bundles and interlobular septa (five patients). Pathologically, solitary nodular lesions consisted of diffuse lymphoplasmacytic infiltration with fibrosis. Thickened bronchovascular bundles or interlobular septa and GGO on CT images pathologically corresponded to lymphoplasmacytic infiltration and fibrosis in peribronchiolar or interlobular interstitium and alveolar interstitium, respectively. The radiologic findings of honeycombing corresponded to disrupted alveolar structures and dilated peripleural air spaces. CONCLUSION IgG4-related lung disease manifested as four major categories of CT features. Pathologically, these features corresponded to IgG4-related sclerosing inflammation along the intrapulmonary connective tissue.

IgG4-Related Disease: Dataset of 235 Consecutive Patients

AbstractImmunoglobulin G4-related disease (IgG4-RD) is a recently discovered systemic condition, in which various organ manifestations are linked by a similar histological appearance. Our knowledge of this condition is still fragmented, as most studies have examined only a few dozen patients or focused on a particular organ manifestation. This study was conducted to learn the demography and patient characteristics of IgG4-RD using a large cohort. A total of 235 consecutive patients with IgG4-RD, diagnosed in 8 general hospitals in the same medical district, were identified by searching the institutions’ radiology database. Inclusion criteria were histology-proven IgG4-RD according to the Pathology Consensus Statement and/or definitive type 1 autoimmune pancreatitis meeting the International Consensus Diagnostic Criteria. Clinical notes and images of selected patients were retrospectively reviewed. All patients were adults (M/F = 4/1). The median age was 67 years (range 35–86). Nine tenths were diagnosed in their 50s to 70s. Among 486 manifestations identified in total, the most common was pancreatitis diagnosed in 142 patients (60%), followed by sialadenitis (34%), tubulointerstitial nephritis (23%), dacryoadenitis (23%), and periaortitis (20%). The majority of patients (95%) had at least 1 of the 5 most common manifestations. Male and female patients differed in their organ manifestations (periaortitis more common in males and sialodacryoadenitis more common in females). Serum IgG4 (normal ⩽135 mg/dL) was elevated to >135 mg/dL in 208 patients (88%) and >270 mg/dL in 167 (71%). The IgG4 value was significantly higher in patients with multiorgan involvement than in those with a single manifestation (median 629 mg/dL vs 299 mg/dL, P < 0.01). Of 218 patients, for whom both IgG4 and IgG values were available, the IgG4/IgG ratio was raised to >10% in 194 (89%). Corticosteroids were effective, but the relapse rate was estimated to be 24% in the study period (median 37 months). During the follow-up, 15 malignant diseases were diagnosed in 13 patients (6%). This figure is similar to the incidence (12.9 cancers) expected from the Japanese nationwide study for cancer epidemiology (standardized incidence ratio 1.16). In conclusion, this reliable dataset could improve the characterization of IgG4-RD, particularly its unique demography and the frequency of each organ manifestation.

Immunoglobulin G4–related Periaortitis and Periarteritis: CT Findings in 17 Patients

PURPOSE To retrospectively evaluate computed tomographic (CT) findings of immunoglobulin G4 (IgG4)-related disease involving the vascular system. MATERIALS AND METHODS This study was approved by the institutional review board, and all patients included had consented to the use of their medical records for the purpose of research. The study consisted of 17 patients (16 men and one woman; age range, 54-86 years). CT findings of IgG4-related periarterial lesions were retrospectively analyzed. Radiopathologic correlations were examined on the basis of surgically resected specimens. RESULTS A total of 22 periarterial lesions were detected in 17 patients. The lesions were located in the thoracic aorta (n = 4), abdominal aorta to iliac arteries (n = 13), superior mesenteric artery (n = 3), inferior mesenteric artery (n = 1), and splenic artery (n = 1). Radiologically, they were characterized by arterial wall thickening (mean thickness, 11 mm), relatively clear circumscription, possible association with luminal change (mostly dilated and rarely stenotic), exaggerated atherosclerotic change, and homogeneous enhancement at the late phase of contrast material-enhanced CT. Twelve patients (71%) had IgG4-related disease in other organs. Pathologically, diffuse lymphoplasmacytic infiltration, numerous IgG4-positive plasma cells, and irregular fibrosis were noted in the thickened arterial wall, especially at the adventitia. Steroid therapy administered to eight patients rapidly diminished the arterial wall thickening. One patient who did not receive steroid therapy showed spontaneous improvement at follow-up CT. CONCLUSION IgG4-related arterial lesions occur mainly in the aorta and its main branches and are radiologically characterized by homogeneous arterial wall thickening corresponding to pathologic features of IgG4-related sclerosing inflammation in the adventitia.

Extrahepatic Blood Supply to Hepatocellular Carcinoma: Angiographic Demonstration and Transcatheter Arterial Chemoembolization

PurposeTo evaluate the incidence of each extrahepatic collateral pathway to hepatocellular carcinoma (HCC) and to assess technical success rates and complications of transcatheter arterial chemoembolization (TACE) through each collateral.MethodsWe retrospective evaluated extrahepatic collateral pathways to HCC on angiography in 386 procedures on 181 consecutive patients. One hundred and seventy patients had previously undergone TACE. TACE through extrahepatic collaterals using iodized oil and gelatin sponge particles was performed when a catheter was advanced into the tumor-feeding branch to avoid nontarget embolization.ResultsA single collateral was revealed in 275 TACE procedures, two were revealed in 74, and three or more were revealed in 34. Incidences of collateral source to HCC were 83% from the right inferior phrenic artery (IPA), 24% from the cystic artery, 13% from the omental artery, 12% from the right renal capsular artery (RCA) and left IPA, 8% from the right internal mammary artery (IMA) and right intercostal artery (ICA), and 7% from the right inferior adrenal artery (IAA). Technical success rates of TACE were 53% in the right ICA, 70% in the cystic artery, 74% in the omental artery, 93% in the left IPA, 96% in the right IPA, and 100% in the right RCA, right IMA, and right IAA. Complications included skin necrosis after TACE through the right IMA (n = 1), cholecystitis after TACE through the cystic artery (n = 1), and ulcer formation after TACE through the right gastric artery (n = 1), in addition to pleural effusion and basal atelectasis after TACE through the IPA and IMA.ConclusionOur study suggests that TACE through extrahepatic collaterals is possible with high success rates, and is also relatively safe.

Multicentric Castleman's disease with abundant IgG4-positive cells: a clinical and pathological analysis of six cases

Background Differentiation between multicentric Castlemans disease and systemic immunoglobulin (Ig) G4-related lymphadenopathy is sometimes difficult. It has been suggested that measurement of the IgG4-/IgG-positive cell ratio is useful for the differential diagnosis of the two diseases. However, the authors present a detailed report of six patients with multicentric Castlemans disease with abundant IgG4-positive cells (IgG4-/IgG-positive cell ratio, >40%). Results In the present series, the patients showed systemic lymphadenopathy, polyclonal hypergammaglobulinaemia and elevated serum interleukin-6 (IL-6) and C-reactive protein levels. Further, anaemia, hypoalbuminaemia, hypocholesterolaemia and thrombocytosis were observed. These findings were consistent with those of multicentric Castlemans disease. Although five patients showed elevated serum IgG4 levels, only two patients showed an increased serum IgG4/IgG ratio. However, the two patients showed highly elevated serum IgG4 levels, but the serum IgG4/IgG ratios were, although increased, not very high. Also, a patient with increased serum IgG4/IgG ratio showed a good response to antihuman IL-6 receptor monoclonal antibody (tocilizumab). Histologically, the germinal centres were mostly small and regressive, and frequently penetrated by hyalinised blood vessels, and there was no eosinophil infiltration. These findings were different from those of IgG4-related lymphadenopathy. Conclusions The authors conclude that multicentric Castlemans disease sometimes occurs with abundant IgG4-positive cells and elevated serum IgG4 levels. Therefore, the two diseases cannot be differentially diagnosed by immunohistochemical staining alone. Laboratory findings, especially IL-6 level, C-reactive protein level and platelet count, are important for the differential diagnosis of the two diseases.

IgG4-Related Perineural Disease

Aims. To elucidate characteristics of IgG4-related disease involving the peripheral nervous system. Methods. Retrospective review of 106 patients with IgG4-related disease identified 21 peripheral nerve lesions in 7 patients. Clinicopathological and radiological features were examined. Results. Peripheral nerve lesions were commonly identified in orbital or paravertebral area, involving orbital (n = 9), optic (n = 4), spinal (n = 7), and great auricular nerves (n = 1). The predominant radiological feature was a distinct perineural soft tissue mass, ranging 8 to 30 mm in diameter. Histologically, the epineurium was preferentially involved by massive lymphoplasmacytic infiltration rich in IgG4+ plasma cells. All lesions were neurologically asymptomatic and steroid-responsive at the first presentation, but one recurrent lesion around the optic nerve caused failing vision. Conclusion. IgG4-related disease of the peripheral nervous system is characterized by orbital or paravertebral localization, perineural mass formation, and rare neurologic symptoms. The term “IgG4-related perineural disease” seems appropriate to describe this entity.

Retroperitoneal and aortic manifestations of immunoglobulin G4-related disease

Retroperitoneal fibrosis is one of the prototypic manifestations of immunoglobulin G4 (IgG4)-related disease (IgG4-RD), but there is growing evidence that the aorta is also involved. These 2 conditions are closely linked, and based on the epicenter of the disease, the clinical manifestations can be classified as retroperitoneal fibrosis, inflammatory abdominal aortic aneurysm (including a combination of the 2), and thoracic aortitis. IgG4-RD is responsible for only a subset (∼50%) of cases of retroperitoneal fibrosis and inflammatory aortic aneurysms. Histological features include an extensive lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells, fibrosis arranged in a storiform pattern, moderate tissue eosinophilia, and partially or completely obliterated veins. Among the 3 layers comprising the aorta, the adventitia is most susceptible to IgG4-related inflammation. The inflammatory process can also disrupt the lamellar elastic fibers in the media, which is seemingly a critical event leading to aneurysmal transformation. Steroid therapy is effective for both retroperitoneal and aortic lesions, as it is for the other manifestations of IgG4-RD. The risk of rupture appears to be low in patients with IgG4-related aortic aneurysms, but immunosuppressive therapy may trigger this critical complication by reducing the wall thickness.