Are Sjögren's syndrome and IgG4-related disease able to coexist?

A case with overlapping features of IgG4-related autoimmune pancreatitis, Sjögren's syndrome and anti-aminoacyl-tRNA synthetase syndrome

A 55-year-old man who had been diagnosed with autoimmune pancreatitis five years earlier was referred to our department because of finger swelling, finger stiffness and the presence of interstitial lung disease (ILD). The patient was diagnosed with Sjögren's syndrome according to the pathological findings of minor salivary glands and positive anti-SS-A antibodies. Later, at age 58, he was hospitalised due to the exacerbation of the ILD. Serum IgG4 level was checked and was found to be elevated (417 mg/dL). After the introduction of cyclosporine in addition to the prednisolone, at age 60, the ILD disease activity stabilised. However, at age 62, fever, myalgia and mechanic's hands appeared. His serum creatine kinase level was high, and magnetic resonance imaging showed inflammatory findings of muscle. In-house ELISA clarified that his serum carried anti-PL-7 antibody among anti-aminoacyl-tRNA synthetase antibodies. This is a unique case who had overlapping features of IgG4-related autoimmune pancreatitis, Sjögren's syndrome and anti-synthetase syndrome. Although the aetiology of the complications in this patient is obscure, autoimmunity might have played a significant role in the disease conditions and prognosis of the present case with IgG4-related disease.

[Clinical and laboratory characteristics of IgG4-realated disease and its diagnostic algorithm]

AIM

to propose diagnostic algorithm of IgG4-related disease (IgG4-RD).

MATERIALS AND METHODS

One center retrospective research. 52 pts with IgG4-RD were included. The diagnosis was proved histologically and immunohistochemically. 48 out of 52 pts received treatment. Treatment included one of the following schemes (along with low oral glucocorticoids): rituximab monotherapy, cyclophosphamide monotherapy or their combination.

RESULTS

The mean age was 47.4±5.9 years, the mean age of the disease onset was 43.9±16.0 years. Median time before the diagnosis was 24 months. The most often sites of IgG4-RD were lacrimal (63.5%), salivary (46.2%) glands, lungs (48%), lymph nodes (34.6%) and retroperitoneum (17.3%). In clinical picture the leading complain was organ enlargement, but not its dysfunction. Pain was characteristic for retroperitoneum localization. In 56.8% of pts with IgG4-related syalo - and/or dacryoadenitis there was association with ear - nose - throat organs affection. In 4 pts (7.7%) IgG4-RD was combined with some malignant disease, including MALT-lymphoma of lacrimal glands. Irreversible organ damage as an IgG4-RD outcome had 15.4% of pts. The main laboratory markers of IgG4-RD were ESR elevation (38.5%), blood eosinophilia (9.6%), immunological disturbances (serum total IgG and IgG4 elevation, IgE elevation, antinuclear antibodies, rheumatoid factor detection, hypocomplementemia). Serum IgG4 level >1.35 g/l was elevated in 88% of pts and correlated with the number of affected organs (Spearman correlation coefficient 0.39, Student's test, р=0.0056). Monoclonal serum secretion and B-cell clonality in the tissue was detected in 4 (23.5%) out of 17 pts, but not all of them had both signs.

CONCLUSION

Based on the analysis of clinical and laboratory characteristics of IgG4-RD a diagnostic algorithm was proposed that enhances the detection and examination of the patients with suspected IgG4-RD.

Salivary Gland Pathology in IgG4-Related Disease: A Comprehensive Review

IgG4-related disease (IgG4-RD) is a rare fibroinflammatory condition that can affect almost any organ, characterized by swollen lesions and often by eosinophilia and elevated serum IgG4 concentrations. The diagnosis of IgG4-RD is a challenging task: in fact, single or multiple organs can be affected and clinical, serological, and histological findings can be heterogeneous. In IgG4-RD, the involvement of salivary glands is observed in 27% to 53% of patients. Several organ-specific conditions, now recognized as different manifestations of IgG4-related sialadenitis (IgG4-RS), were viewed in the past as individual disease entities. The study of salivary glands may sometimes be complex, because of the number of pathological conditions that may affect them, often with overlapping clinical pictures. Integration of different imaging techniques is often required in the case of swelling of salivary glands, even though biopsy remains the gold standard for a definite diagnosis of IgG4-RS. Thus, in this review, we discuss new insights in the pathogenesis of IgG4-RD, focusing on its clinical aspects and the tools that are currently available for a correct differential diagnosis when the salivary glands are involved.

Differential diagnosis of IgG4-related sialadenitis, primary Sjögren syndrome, and chronic obstructive submandibular sialadenitis

Our aim was to differentiate IgG4-related sialadenitis, primary Sjögren syndrome, and chronic obstructive submandibular sialadenitis by analysing clinical, radiographic, and pathological features. Fifty-five patients, 50, and 50 were enrolled, respectively and their baseline characteristics and serological, sialographic, and pathological findings compared. The male:female ratio for IgG4-related sialadenitis was 1:1.2 for primary Sjögren syndrome 1:15.7, and for chronic obstructive submandibular sialadenitis1:0.92. Numbers with enlarged salivary glands were 55, 16, and 50; with xerostomia 26, 48, and 0; with a history of allergy 26, 4, and 6, and with coexisting systemic disease 12, 19, and 0 (p=0.14). Mean (SD) serum IgG4 concentrations were 109.1 (97.9), 4.9. (1.9) g/L, and 5.3 (1.6) g/L, p<0.001 in all cases. Sialography showed enlargement of the gland, dilatation of the duct, and slightly decreased secretory function in IgG4-related disease; obvious sialectasia and decreased secretory function in Sjögren syndrome; and dilatation of Wharton's duct and filling defects in obstructive sialadenitis. Histopathological examination showed lymphoplasmacytic infiltration with storiform fibrosis, lymphoplasmacytic inflammation and lymphoepithelial lesions, and dilatation of the duct with epithelial metaplasia in the three groups, respectively. The number of IgG4-positive plasma cells was 123 (45)/HPF, 8 (3)/HPF, and 5 (4)/HPF, while the IgG4-/IgG-positive cell ratio was 71.7 (13.9)%, 4.6 (2.5)%, 18.9 (19.7)%, respectively (p<0.001). The three conditions have different clinical, radiographic, and pathological features that provide important clues to the differential diagnosis. Serological and histological tests are important, and comprehensive consideration is necessary.

Overview of IgG4-Related Tubulointerstitial Nephritis and Its Mimickers

Tubulointerstitial nephritis (TIN) is the most common form of renal involvement in IgG4-related disease. It is characterized by a dominant infiltrate of IgG4-positive plasma cells in the interstitium and storiform fibrosis. Demonstration of IgG4-positive plasma cells is essential for diagnosis, but the number of IgG4-positive cells and the ratio of IgG4-positive/IgG-positive plasma cells may vary from case to case and depending on the methods of tissue sampling even in the same case. IgG4-positive plasma cells can be seen in TIN associated with systemic lupus erythematosus, Sjögren syndrome, or anti-neutrophil cytoplasmic antibody–associated vasculitis, which further add diagnostic confusion and difficulties. To have a more clear view of IgG4-TIN and to delineate differential points from other TIN with IgG4-positive plasma cell infiltrates, clinical and histological features of IgG4-TIN and its mimickers were reviewed. In the rear part, cases suggesting overlap of IgG4-TIN and its mimickers and glomerulonephritis associated with IgG4-TIN were briefly described.