IgG4‐related sialadenitis and Sjögren's syndrome

Abstract

IgG4-related disease (IgG4-RD) has emerged as a new entity in the last decade. It comprises numerous conditions previously thought to be unrelated. Macroscopically, these diseases cause diffuse organ swelling and formation of pseudotumorous masses. Histopathologically, they are characterized by a lymphoplasmacytic infiltrate with increased IgG4+ plasma cells and storiform fibrosis. Despite rapid progress within the last years, our knowledge on these conditions is still fragmented. To date, more than forty organs have been reported to be included in IgG4-RD, and salivary gland involvement is amongst the most common organs affected [IgG4-related sialadenitis (IgG4-RS)]. Interestingly, IgG4-RS shares commonalities with Sjögren's syndrome (SS), like glandular enlargement, sicca symptoms, arthralgias, hypergammaglobulinemia, hypocomplementemia, and circulating antinuclear antibodies. Nonetheless, they differ in that the incidence of anti-Ro and anti-La reactivity is not frequently found in patients with IgG4-RS, their salivary glands are infiltrated by a large number of IgG4+ plasma cells and IgG4-RS symptoms respond promptly to steroids. The aim of this review was to describe the clinical, serological, histopathological and pathophysiological aspects of IgG4-RS in the context of IgG4-RD and highlight the differences between IgG4-RS and SS.

Sialendoscopic management of autoimmune sialadenitis: a review of literature

“…This is contrary to most autoimmune disorders where polarised Th1 and/or Th17 subsets are responsible for the inflammatory process 2 3 47 .…”

“…On the contrary, a nodular pattern with duct enlargement and microlithiasis is often observed in the disorder once known as KT. Computerised tomography and magnetic resonance imaging have lower diagnostic accuracy compared to ultrasonography 2 3 51 - 56 .…”

“…For this special feature, IgG4 scarcely forms immune complexes, binds Fc-receptors and complements component with low affinity. Thus, its ability to initiate immune responses is limited 2 3 .…”

“…In these conditions, the parenchyma of salivary glands, salivary ducts, or both represent the target of an attack carried out by the immune system against its own tissues, through autoantibodies and T cells. Sjögren's syndrome (SS) and immunoglobulin G4-related diseases (IgG4-RD) are the main chronic autoimmune sialadenitis 1 2 .…”

The oral mucosa: A barrier site participating in tissue‐specific and systemic immunity

“…One‐third of patients with Sjögren's syndrome presents with intermittent or persistent major salivary gland enlargement. For diagnosis, other conditions manifesting with dry mouth and/or major salivary gland enlargement (such as sarcoidosis, HIV/HCV infection, and IgG4‐related sclerosing sialadenitis (Mikulitz syndrome and lymphoma) should be ruled out (Ramos‐Casals, Brito‐Zeron, & Font, ) (Fragoulis, Zampeli, & Moutsopoulos, ).…”