Novel Use of Rituximab in a Case of Riedel's Thyroiditis Refractory to Glucocorticoids and Tamoxifen

Abstract

A 42-year-old woman presented with a rapidly enlarging right-sided thyroid mass and underwent hemithyroidectomy. Riedel's thyroiditis was only diagnosed upon surgical decompression of the right carotid artery 2 years later. She became more symptomatic as Riedel's thyroiditis progressed, and mediastinal fibrosclerosis developed over the next 12 months. Oral prednisolone failed to improve her condition, and she was commenced on tamoxifen. Despite initial improvement, her symptoms recurred 2 years later, mainly arising from compression of the trachea and esophagus at the thoracic inlet. Fluorodeoxyglucose positron emission tomographic scan showed locally advanced active invasive fibrosclerosis in the neck and mediastinum. An elevated activin-A level of 218 pg/mL was consistent with active inflammation. IgG subtypes (including IgG4) were normal. Two courses of iv methylprednisolone were given but only produced transient improvement. Subsequently, the patient received 3 doses of i.v. rituximab at monthly intervals and had prompt sustained symptomatic improvement. Activin-A level decreased to 122 pg/mL 10 months after rituximab therapy. Fluorodeoxyglucose positron emission tomographic scan 6 weeks after therapy showed reduction in inflammation. A further scan at 10 months demonstrated ongoing response to rituximab. This is a case of refractory Riedel's thyroiditis with symptomatic, biochemical, and radiological improvement that has persisted 14 months after rituximab. The likelihood and duration of response to rituximab in Riedel's thyroiditis requires further study.

Riedel's thyroiditis association with IgG4-related disease

“…On the other hand, findings from a recently conducted single‐arm trial of rituximab used for IgG4‐RD have shown promising results in terms of remission of disease . While no patient with RT has been included in that trial, we are aware of one case report that describes the effective use of rituximab in a single RT patient refractory to tamoxifen and glucocorticoid treatment . Unfortunately, no other trial of antifibrotic therapy for RT has been completed to date.…”

Thyroid function, autoimmunity and nodules in hematological malignancies

“…Thyroid investigations in patients with hematological disorders have essentially focused on the thyroid complications ensuing from chemotherapy and/or external irradiation (4)(5)(6)(7)(8)(9)(10)14,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). Because no study has simultaneously taken care of all clinically relevant thyroid aspects (namely, function, autoimmunity and nodules), we have conducted such a study on hematoncologic patients excluding those who had been treated with external irradiation.…”

Clinicopathological features of Riedel’s thyroiditis associated with IgG4-related disease in Japan

“…Thus, extra-thyroid organ involvement and the presence of IgG4-positive plasma cells both predict a good response to steroid therapy in patients with RT. In patients refractory to the steroid therapy, tamoxifen and rituximab have been reported to be effective [7,30,31].…”