Tertiary lymphoid structures (TLS) are organized lymphoid‒like aggregates found in non‒lymphoid tissues. TLS typically form in areas with persistent inflammation infiltration. Growing evidence suggests that TLS are associated with a variety of diseases or conditions, such as malignancy, autoimmune disease, transplant rejection, infection and age‒related chronic inflammatory condition. The presence of TLS correlates with favorable disease outcomes in patients with malignancy or infection. Conversely, in autoimmune diseases, including connective tissue diseases, TLS are shown to contributes to the disease pathogenesis, but the detailed mechanisms underlying formation of TLS and their roles in the pathogenic process are not fully understood. This review article summarizes recent findings on adaptive immune responses occurring in the TLS in patients with rheumatoid arthritis, Sjögren's disease, lupus nephritis, IgG4‒related dacryoadenitis and sialadenitis, or idiopathic inflammatory myositis, including our own studies on cancer‒associated myositis.

For the diagnosis of immunoglobulin G4 (IgG4)-related dacryoadenitis and sialadenitis, either revised comprehensive diagnostic criteria or organ-specific diagnostic criteria for IgG4-related dacryoadenitis and sialadenitis in 2008 were applied; however, the collected knowledge for IgG4-related dacryoadenitis and sialadenitis required us to revise the criteria for IgG4-related dacryoadenitis and sialadenitis. The board member of Japanese Study Group for IgG4-related Dacryoadenitis and Sialadenitis revised the diagnostic criteria for IgG4-related dacryoadenitis and sialadenitis. We collected the clinical questions to be revised and performed a review of the literature. When the data were insufficient, additional data collection was performed. After the revision, public comments were collected. The three major points were revised. (1) Asymmetric or under two pairs of dacryoadenitis and sialadenitis were included as IgG4-related dacryoadenitis and sialadenitis. (2) The thresholds of IgG4-positive cell infiltration were adjusted to an IgG4+/IgG+ ratio >0.4 and IgG4+ cells >10 per high power field. (3) The labial salivary gland biopsy was allowed to diagnose IgG4-related dacryoadenitis and sialadenitis. The revised diagnostic criteria for IgG4-related dacryoadenitis and sialadenitis solved several issues with the previous criteria. It will improve the early diagnosis of IgG4-related dacryoadenitis and sialadenitis, especially in situations without enough resources for a biopsy.

We report a case of IgG4-related dacryoadenitis and sialadenitis (Mikulicz's disease) with acquired hemophilia A (AHA) in a pediatric patient. An 11-year-old female presented with intermittent swelling of the bilateral upper eyelids and neck areas. Clinical examination revealed bilateral swollen upper eyelids with palpable mass lesions in the lacrimal fossa. The submandibular and sublingual glands were enlarged, tender, and movable. Neck ultrasound showed bilateral gland enlargement with irregular hypoechoic parenchyma. Maxillofacial magnetic resonance imaging (MRI) revealed bilateral lacrimal glands enlargement, homogeneous enlarged bilateral submandibular and parotid glands, measuring 4.7 × 3.9 cm. Laboratory investigation showed increased activated partial prothromboplastin time (80.9 s), markedly decreased FVIII activity (0.6%), a high titer of FVIII inhibitor (480 Bethesda units/mL), and a remarkable increase in serum IgG4 level (1005.68 mg/dL). A left submandibular gland biopsy revealed marked lympho-plasmacytic infiltration with scattered eosinophils. Immunohistochemical staining for IgG4 showed numerous IgG4-positive plasma cells (>100 per high-power field), with a ratio of IgG4-positive to IgG-positive cells >40%. The symptoms were markedly relieved following corticosteroid therapy. IgG4-related dacryoadenitis and sialadenitis (Mikulicz's disease) with acquired hemophilia A (AHA) can also be seen in the pediatric population and should be considered a differential diagnosis in patients with relevant symptoms.

To identify the specific microRNAs (miRNAs) in IgG4-related dacryoadenitis and sialadenitis (IgG4-DS) and predict the targeted genes. miRNAs in the serum of nine patients with IgG4-DS, three patients with primary Sjögren's syndrome, and three healthy controls were analysed using the human miRNA chip, and miRNAs that exhibited significant fluctuation in expression in IgG4-DS patients were extracted. The respective target genes were predicted using an existing database, and expression of the target genes was evaluated in actual submandibular gland tissues affected by IgG4-DS. Serum miR-125a-3p and miR-125b-1-3p levels were elevated in IgG4-DS. Six candidate target genes (glypican 4, forkhead box C1, protein tyrosine phosphatase non-receptor type 3, hydroxycarboxylic acid receptor 1, major facilitator superfamily domain containing 11, and tumour-associated calcium signal transducer 2) were downregulated in the affected submandibular gland tissue. Overexpression of miR-125a-3p and miR-125b-1-3p is a hallmark of IgG4-DS. These miRNAs appear to be involved in the pathogenesis of IgG4-DS.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic inflammatory disease characterized by the infiltration of IgG4-positive plasma cells and fibrosis in organs throughout the body. IgG4-RD involvement in the gastrointestinal (GI) tract (IgG4-related GI disease; IgG4-GID) is rare, and the disease concept remains unclear. Generally, IgG4-GID has been reported with morphological changes, including ulcers, strictures, and submucosal tumors. Here, we report a case of IgG4-GID with persistent diarrhea and abdominal pain in which typical endoscopic findings were absent. This case suggests the unidentified clinical features of IgG4-GID.