IgG4 multiorgan lymphoproliferative syndrome as a differential diagnosis of primary Sjogren's syndrome in men?

Sjögren syndrome

Sjögren syndrome (SjS) is a systemic autoimmune disease that primarily affects the exocrine glands (mainly the salivary and lacrimal glands) and results in the severe dryness of mucosal surfaces, principally in the mouth and eyes. This disease predominantly affects middle-aged women, but can also be observed in children, men and the elderly. The clinical presentation of SjS is heterogeneous and can vary from sicca symptoms to systemic disease (characterized by peri-epithelial lymphocytic infiltration of the affected tissue or the deposition of the immune complex) and lymphoma. The mechanism underlying the development of SjS is the destruction of the epithelium of the exocrine glands, as a consequence of abnormal B cell and T cell responses to the autoantigens Ro/SSA and La/SSB, among others. Diagnostic criteria for SjS include the detection of autoantibodies in patient serum and histological analysis of biopsied salivary gland tissue. Therapeutic approaches for SjS include both topical and systemic treatments to manage the sicca and systemic symptoms of disease. SjS is a serious disease with excess mortality, mainly related to the systemic involvement of disease and the development of lymphomas in some patients. Knowledge of SjS has progressed substantially, but this disease is still characterized by sicca symptoms, the systemic involvement of disease, lymphocytic infiltration to exocrine glands, the presence of anti-Ro/SSA and anti-La/SSB autoantibodies and the increased risk of lymphoma in patients with SjS.

Elevated IgG4 serum levels among primary Sjögren's syndrome patients: do they unmask underlying IgG4-related disease?

OBJECTIVE

To determine IgG4 levels in a cohort of consecutive patients with primary Sjögren's syndrome (SS) and other autoimmune diseases and explore whether they associate with distinct clinical, serologic, and histopathologic features.

METHODS

Serum IgG4 levels were measured in 133 primary SS patients and 49 healthy donors (HDs). Seventy-four lupus and 54 rheumatoid arthritis (RA) patients served as disease controls. Immunohistochemical IgG4 analysis was performed in paraffin-embedded minor salivary gland (MSG) tissues.

RESULTS

Raised IgG4 serum levels (>135 mg/dl) were detected in 10 (7.5%) of 133 primary SS patients (high-IgG4 group), in 8 (10.8%) of 74 lupus patients, in 7 (12.9%) of 54 RA patients, and in 1 (2%) of 49 HDs. Compared to the normal-IgG4 (<135 mg/dl) primary SS group, high-IgG4 patients exhibited increased prevalence of IgG4-related features (autoimmune cholangitis, autoimmune pancreatitis, and interstitial nephritis), lower rates of antinuclear antibody positivity, and higher IgG2 and IgE levels. Positive staining for IgG4+ plasma cells with an IgG4:IgG ratio ≥40% was detected in 3 of 6 available MSG tissues in the high-IgG4 group. Criteria of possible or definite IgG4-related disease (IgG4-RD) were fulfilled by 10 (7.5%) of 133 of our primary SS cohort.

CONCLUSION

Raised IgG4 serum levels were detected in 7.5% of primary SS patients in association with IgG4RD-reminiscent clinical, serologic, and histopathologic features. Whether this high-IgG4 primary SS group represents a misclassified IgG4-RD group or a distinct primary SS subtype remains to be further explored in future studies.