Supraphysiological doses of glucocorticoids induce remission in a patient with retroperitoneal fibrosis but no effect on the course of Hashimoto’s thyroiditis: a discordant mode of action

Glucocorticoids (GC) are widely used to treat autoimmune diseases. We describe the discordant mode of action of GC in retroperitoneal fibrosis (RPF) and Hashimoto's thyroiditis (HT) in this work. A 48-year-old woman presented with abdominal pain. Detailed evaluation confirmed a retroperitoneal infiltrative lesion. Positron emission tomography (PET) scan revealed a hypermetabolic soft tissue mass within the retroperitoneal area and a diffusely hypermetabolic thyroid gland–TFT normal; TPO Ab >600 IU/mL; TgAb 14.4 I U/mL. Diagnoses of HT and idiopathic RPF were made, and she was treated with prednisone. Abdominal infiltrative process improved; however, thyroid ultrasound and PET scan showed no change in thyroid features. Glucocorticoid treatment resulted in remission of RPF, but not HT. The exact pathophysiological mechanism underlying the non-response to GC treatment in patients with HT remains unknown. Our case exhibits the interesting discordant mode of action of GC in RPF and HT.