[A case of Mikulicz's disease complicated by autoimmune pancreatitis, in which impaired glucose tolerance was improved by glucocorticoid treatment]

Mechanisms and assessment of IgG4-related disease: lessons for the rheumatologist

Recognition of IgG4-related disease as an independent chronic inflammatory disorder is a relatively new concept; previously, the condition was thought to represent a subtype of Sjögren's syndrome. IgG4-related disease is characterized by elevated serum levels of IgG4 and inflammation of various organs, with abundant infiltration of IgG4-bearing plasma cells, storiform fibrosis and obliterative phlebitis representing the major histopathological features of the swollen organs. The aetiology and pathogenesis of this disorder remain unclear, but inflammation and subsequent fibrosis occur due to excess production of type 2 T-helper-cell and regulatory T-cell cytokines. The disease can comprise various organ manifestations, such as dacryoadenitis and sialadenitis (also called Mikulicz disease), type 1 autoimmune pancreatitis, kidney dysfunction and lung disease. Early intervention using glucocorticoids can improve IgG4-related organ dysfunction; however, patients often relapse when doses of these agents are tapered. The disease has also been associated with an increased incidence of certain malignancies. Increased awareness of IgG4-related disease might lead to consultation with rheumatologists owing to its clinical, and potentially pathogenetic, similarities with certain rheumatic disorders. With this in mind, we describe the pathogenic mechanisms of IgG4-related disease, and outline considerations for diagnosis and treatment of the condition.

The birthday of a new syndrome: IgG4-related diseases constitute a clinical entity

IgG4-related disease is a distinct clinical entity, whose characteristic features are the following; Serum IgG4 is prominently elevated, IgG4-positive plasma cells infiltrate in involved tissues, various mass-forming lesions with fibrosis develop in a timely and spatial manner and the response to corticosteroids is prompt and good. IgG4-related diseases mainly target two organs. One is the pancreas (autoimmune pancreatitis; AIP), and the other comprises the lacrimal and salivary glands, the clinical phenotype is Mikulicz's disease (MD). MD has long been considered a manifestation of Sjögren's syndrome (SS). However, we noticed several clinical differences in case of MD from SS; no deflection of female sex differences, mild sicca syndrome, good response to corticosteroids, no positivity of anti-SS-A/SS-B antibodies. In addition, elevated level of serum IgG4 and abundant infiltration of plasma cells expressing IgG4 were reported in MD patients. Those are common features of IgG4-related diseases. MD often coexisted with IgG4-related diseases such as AIP, retroperitoneal fibrosis, and IgG4-associated nephropathy. Based on those findings, it has been considered to recognize IgG4-related diseases including MD as a new clinical entity. The etiology of IgG4-related systemic diseases remains to be elucidated. It is necessary to accumulate and analyze larger data from patients worldwide.

Sonographic diagnosis for Mikulicz disease

OBJECTIVE

The aim was to investigate the diagnostic imaging characteristics of Mikulicz disease (MD), especially sonographic ones, and to clarify the differences between them and those in Sjögren syndrome (SS), based on new criteria of MD.

STUDY DESIGN

The sonographic and sialographic images, as well as clinical, histopathologic, and serologic findings of 9 patients satisfying the new criteria of MD were analyzed and compared with those in SS.

RESULTS

All swollen submandibular glands showed bilateral nodal hypoechoic areas with high vascularization on sonograms and a parenchymal defect on sialograms, whereas parotid glands showed normal or slight change on both images. Nodal areas in submandibular gland sonograms were unclear on computerized tomography and on magnetic resonance imaging, but showed accumulation on gallium scintigraphy.

CONCLUSION

Mikulicz disease showed a high rate of bilateral nodal change in submandibular glands, which was completely different from SS. For detection and follow-up of these changes, sonography may be the best imaging modality.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

A new conceptualization for Mikulicz's disease as an IgG4-related plasmacytic disease

Mikulicz's disease (MD) has been included within the diagnosis of primary Sjögren's syndrome (SS), but it represents a unique condition involving persistent enlargement of the lacrimal and salivary glands characterized by few autoimmune reactions and good responsiveness to glucocorticoids, leading to the recovery of gland function. Mikulicz's disease was recently reported to be associated with elevated immunoglobulin G4 (IgG4) concentrations in the serum and prominent infiltration of plasmacytes expressing IgG4 into the lacrimal and salivary glands. The following features were used for diagnosis: (1) visual confirmation of symmetrical and persistent swelling in more than two lacrimal and major salivary glands; (2) prominent mononuclear cell infiltration of lacrimal and salivary glands; and (3) exclusion of other diseases that present with glandular swelling, such as sarcoidosis and lymphoproliferative disease. These features are not observed in most SS cases. The complications of MD include autoimmune pancreatitis, retroperitoneal fibrosis, tubulointerstitial nephritis, autoimmune hypophysitis, and Riedel's thyroiditis, all of which show IgG4 involvement in their pathogenesis. Mikulicz's disease thus differs from SS and may be a systemic IgG4-related plasmacytic disease.

A case of Mikulicz's disease complicated with interstitial nephritis successfully treated by high-dose corticosteroid

A 40-year-old woman who had bilateral swelling in the eyelids and submandibular region was admitted. Clinical findings suggested she had primary Sjögren's syndrome. Laboratory data showed glucosuria, positive CRP (0.50 mg/dl), liver dysfunction (AST 53 U/l, ALT 101 U/l, gamma-GTP 241 U/l, ALP 914 U/l, LAP 496 U/l), hyperglycemia, hypergammaglobulinemia (IgG 3450 mg/dl, IgA 91 mg/dl, IgM 80 mg/dl), hypocomplementemia (C3 73 mg/dl, C4 2 mg/dl, CH50 < 19.0 U/ml), renal tubular dysfunction (urine N-acetyl-beta-D: -glucosaminidase 8.6 U/l, urine (beta2)-microglobulin 83 microg/l), and urinary concentration defect. Ammonium chloride loading test was normal. Gallium-67 scintigram indicated abnormal uptake in bilateral lacrimal glands, submandibular glands, and kidneys. A diagnosis of Mikulicz's disease and interstitial nephritis was made, since biopsy specimens of her lacrimal gland and minor salivary gland showed diffuse infiltration of lymphocytes. Renal biopsy specimens also showed severe interstitial infiltration of lymphocytes. Symptoms and laboratory data normalized in response to methylprednisolone pulse therapy and prednisolone 60 mg/day. This case of Mikulicz's disease complicated with interstitial nephritis was successfully treated by high-dose corticosteroid.

[The significance of disease-independence in Mikulicz's disease--revival interests in Mikulicz's disease]

Mikulicz's disease represents a unique condition involving enlargement of the lacrimal and salivary glands. Mikulicz's disease has been considered part of primary Sjögren's syndrome because both diseases were histologically similar. However, the gland swellings in Mikulicz's disease are persistent, and its decreased secretional function is good responsiveness to glucocorticoid. Serologically, Mikulicz's disease is characterized by few autoantibody including anti-SS-A and anti-SS-B antibodies. Recently, it is revealed elevated IgG4 concentrations in the serum and prominent infiltration by plasmacytes expressing IgG4 in the lacrimal and salivary glands in Mikulicz's disease. Prominent IgG4-positive plasma cells are also detected in systemic lymph tissues. We cannot detect the phenomenon in Sjögren's syndrome. In complications with Mikulicz's disease, there are autoimmune pancreatitis, retroperitoneal fibrosis, tubulointerstitial nephritis, autoimmune hypophysitis, Riedel's thyroiditis, which are related to IgG4 in its pathogenesis. Mikulicz's disease is different from Sjögren's syndrome, and may be a systemic IgG4-related plasmacytic disease.