Abstract Introduction Cushing's disease (CD) is characterized by exposure to cortisol excess and is caused by excessive secretion of adrenocorticotropic hormone (ACTH) from a pituitary adenoma. The diagnosis, management, and follow – up of patients with Cushing's disease pose significant challenge to clinicians, making it one of the most cumbersome condition in routine endocrinology practice. Here we report an unusual case of CD which underwent remission while on oral treatment. Clinical Case A 23-year-old male presented with hypertensive crisis and weight gain. He had a history of obesity and hypertension for the past eight years. Physical examination revealed central obesity, a buffalo hump, facial acne, and striae around the umbilicus. Initial laboratory tests showed basal cortisol levels of 9.9 and 11.56 µg/dl. Consecutive morning ACTH levels were 24 and 38 pg/ml. The 1 mg dexamethasone suppression test (DST) and the 2-day 2 mg DST showed no suppression (13 and 11 µg/dl, respectively). Urinary free cortisol and late night salivary cortisol levels were increased 2.3 and 3 folds, respectively. These results confirmed the ACTH – dependent cortisol excess. In differential diagnosis of ACTH dependent Cushing’s syndrome, no adenoma detected by pituitary imaging, leading to inferior petrosal sinus sampling (IPSS). The results of IPSS suggested a pituitary source with a central to peripheral ratio greater than 3. Although the patient was referred for pituitary surgery, he did not provide consent for surgical intervention and preferred medical treatment. He was initially started ketoconazole and pasiretoide, but soon after switched to metyrapone due to market shortage of former drugs. The patient experienced a 6-month off period without metyrapone due to an earthquake. Remarkably, during this period without medical therapy, his blood pressure normalized without medication, and there was no recurrence of weight gain, acne, or buffalo hump. Subsequent laboratory tests showed a 1 mg DST result of 0.31 µg/dl, nocturnal serum cortisol of 1.03 µg/dl, and nocturnal salivary cortisol of 0.01 µg/dl (reference range: 0-0.14 µg/dl), and normal UFC levels. Conclusion Spontaneous remission in Cushing's disease is rare, with only a limited number of cases reported in the literature. There have been instances of spontaneous remission following metyrapone treatment. It is hypothesized that metyrapone inhibits steroidogenesis, reducing negative feedback on tumor cells and stimulating increased ACTH synthesis. The resultant increase in ACTH production may heighten the metabolic demands of corticotroph cells, potentially exceeding the blood supply to the pituitary gland, leading to spontaneous infarction of corticotroph cells and subsequent remission of Cushing's disease.
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