Occurrence of De Quervain's Thyroiditis after Resolution of Hypercortisolism following Pasireotide Treatment for Cushing's Disease and Surgery for an Adrenocortical Adenoma: Report of Two Cases.

OBJECTIVE An increased prevalence of thyroid autoimmunity has been observed after successful treatment of Cushing's syndrome. On the other hand, De Quervain's thyroiditis (DQT), in which autoimmunity is not a pathogenetic contributor, has not been reported during recovery from Cushing's syndrome. We describe 2 female patients with DQT coinciding with the resolution of hypercortisolism after treatment of Cushing's syndrome/disease. METHODS The first patient had been diagnosed with Cushing's disease due to a corticotroph pituitary microadenoma, declined neurosurgery, and was receiving pharmacological treatment with pasireotide. Her hypercortisolism was optimally controlled with a minimum dose. The second patient had undergone unilateral adrenalectomy due to a cortisol-secreting adenoma and was on tapering doses of hydrocortisone due to a suppressed corticotroph axis. Both patients presented with clinical, functional, and imaging features of DQT at a time when their endogenous glucocorticoid levels were very low. RESULTS Oral glucocorticoid treatment was administered in both cases, resulting in prompt recovery. CONCLUSIONS The incidence of DQT following the resolution of hypercortisolism, either medical or surgical, has not been previously described. The exact pathogenetic mechanism can only be speculated on. Perhaps the relative or absolute glucocorticoid deficiency after effective treatment of hypercortisolism alters immunologic responses and renders patients more vulnerable to thyrolytic processes.