Immunoglobulin G4-Related Thyroid Diseases.

Area of Science:

• Endocrinology
• Immunology
• Pathology

Background:

• Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory condition with diverse organ manifestations.
• The thyroid gland is frequently involved, leading to IgG4-related thyroid disease (IgG4-RTD), encompassing subtypes like Riedel thyroiditis and fibrosing Hashimoto thyroiditis.
• While IgG4-RD generally affects males, specific thyroid subtypes show a female predominance.

Approach:

• Diagnosis relies on a combination of clinical presentation, serological markers (though serum IgG4 levels are not definitive), and characteristic histological findings with IgG4 immunostaining.
• Imaging modalities aid in diagnosis and disease monitoring.
• Management strategies include first-line steroid therapy, with second-line options like tamoxifen and rituximab for refractory cases.

Key Points:

• IgG4-related thyroid disease (IgG4-RTD) comprises four recognized subcategories: Riedel thyroiditis, fibrosing variant of Hashimoto thyroiditis, IgG4-related Hashimoto thyroiditis, and Graves disease with elevated IgG4.
• The precise pathogenesis of IgG4-RD remains under investigation, with proposed roles for genetic factors, immune responses, and allergic mechanisms.
• Other endocrine system involvements associated with IgG4-RD include hypophysitis and Hashimoto encephalopathy.

Conclusions:

• IgG4-related thyroid disease (IgG4-RTD) is an uncommon but significant entity within the broader IgG4-RD spectrum.
• Prompt recognition and appropriate therapeutic interventions, including corticosteroids and other agents, are essential for managing IgG4-RTD and improving patient prognoses.