Talus Avascular Necrosis as a Rare Complication of Cushing's Disease: A Case Report.

Avascular necrosis (AVN), also called osteonecrosis, stems from blood supply interruption to the bone and is often idiopathic. It has risk factors like trauma, alcohol, and corticosteroids. AVN in the talus (AVNT) is less common than in the femoral head. Most cases of talar osteonecrosis are associated with trauma, while a smaller proportion is linked to systemic conditions such as sickle cell disease or prolonged prednisone use. Glucocorticoids are a key nontraumatic cause. We report a middle-aged woman with Cushing's syndrome symptoms, such as hypertension and moon face, since her youth. A few years ago, she experienced pain and swelling in her ankle, which was diagnosed as atraumatic AVNT and treated with hindfoot fusion. Years later, she was diagnosed with Cushing's disease caused by an adrenocorticotropic hormone (ACTH)-producing pituitary adenoma in laboratory tests and imaging, which was resected in 2020. She experienced significant weight loss, and her Cushing's syndrome symptoms were relieved after tumor resection. Mechanisms behind AVN in hypercortisolism involve fat cell hypertrophy, fat embolization, osteocyte apoptosis, and glucocorticoid-induced hypertension. Traditional X-rays may miss early AVN changes; MRI is preferred for early detection. Although there are some cases of femoral AVN caused by endogenous hypercortisolism in the literature, as far as we know, this is the first case of AVNT due to Cushing's disease. AVNT treatment includes conservative approaches, hindfoot fusion, and core decompression. Cushing's disease is a rare cause of AVNT, and a multidisciplinary approach aids in the rapid diagnosis of elusive symptoms.