Endocrine Abstracts

JOINT126

Introduction: Riedel’s thyroiditis is a rare form of chronic thyroiditis. It is characterised by extensive infiltrative fibrosis of the thyroid and adjacent organs. The aetiopathogenesis has not yet been elucidated. Diagnosis is anatomopathological.

Case Report: 56-year-old female with known diabetis type 2 for 3 months on OAD. Consulted for an anterior basi-cervical swelling, hard, evolving for 1 year without signs of compression. Biologically, she presents with hypothyroidism. Morphologically, a cervical ultrasound showed a lesional process infiltrating the sternohyoid muscle. A thyroid biopsy confirmed the diagnosis of Riedel’s thyroiditis. A CTAP scan ruled out other areas of fibrosis outside the thyroid. The patient was put on corticosteroids.

Discussion: Riedel thyroiditis (RT) represents the classic thyroid form of IgG4 disease. It involves the production of autoantibodies, the exact nature of which remains unclear, which activate B lymphocytes, leading to two distinct immunological responses. In the presence of IL-4 and IL-10 factors from a T helper lymphocyte, the B lymphocyte differentiates into an IgG4-secreting plasma cell. This IgG4, which can be measured in plasma circulation, does not appear to have any immunogenic potential and is only an indirect marker of the infiltrative process caused by the second type of immunogenic response mediated by CD4+ cytotoxic T lymphocytes, leading to the proliferative and/or fibrosing process of IgG4 disease, and therefore to the known clinical manifestations, including TR. In this case, impairment of thyroid and/or parathyroid function depends on the extent of infiltration and thyroid comorbidities (1).

Conclusion: As TR is not yet fully understood, the therapeutic approach remains empirical and imperfect. Corticosteroid therapy is effective in the constitutive phase of the disease, but its value beyond this is more controversial. Tamoxifen is a good alternative. Surgery may be indicated in cases of compression.

Références: Thyroidite De Riedel Marie Champagne, Dr Sylvain Prévost — Université de Sherbrooke.