Combined mycophenolate mofetil and prednisone therapy in tamoxifen- and prednisone-resistant Reidel's thyroiditis

Mycophenolate mofetil is a recently identified therapy for disorders associated with systemic fibrosis, but has never been reported in the treatment of Reidel's thyroiditis. We report the first case of Reidel's thyroiditis that became resectable after treatment with mycophenolate and prednisone.

A 27-year-old woman presented to an outside hospital with thyromegaly associated with compressive symptoms. The patient underwent a neck exploration with thyroid biopsy that revealed evidence of fibrosing variant Hashimoto's thyroiditis. The patient was then treated with tamoxifen and prednisone at an outside hospital without resolution. After initial evaluation she underwent an open thyroid wedge biopsy that revealed Reidel's thyroiditis. She was subsequently treated with both 1 g mycophenolate twice daily and 100 mg prednisone daily. The patient experienced immediate subjective improvement of compressive symptoms and objective decrease in mass size at 30 days, as seen by serial computed tomography examination. By 90 days of therapy the mass had decreased to a size small enough to allow subtotal thyroidectomy, which was completed over two staged procedures.

Reidel's thyroiditis remains a primarily surgical disease. Patients who are not surgical candidates have been treated with tamoxifen and prednisone with equivocal results. Our report is the first to suggest the combination of mycophenolate and prednisone as a viable treatment option for patients with Reidel's thyroiditis.