Abstract
Ectopic adrenocorticotropic hormone (ACTH) syndrome is a challenging diagnosis only responsible for approximately 10% of Cushing syndrome cases. It has been associated with a variety of benign and malignant tumors including a carcinoid tumor accompanied by aspergilloma in our case that was significantly difficult to be detected. We report a patient over 70 years old with uncontrolled hypertension and hypokalemia presenting with generalized edema. Laboratory results revealed ACTH-dependent Cushing syndrome, but imaging studies did not show any discrete lesions secreting ACTH. The petrosal to peripheral ACTH gradient resulted in no evidence of pituitary adenoma. As the only lesion suspicious for ectopic ACTH secretion was a right lower round cystic lesion that did not appear to be a carcinoid tumor on computed tomography scan of the chest, the patient underwent video-assisted thoracic surgical resection to provide a definitive diagnosis. The final diagnosis was a small ectopic ACTH-secreting carcinoid tumor with unusual superimposed aspergilloma in the periphery of the lung. Postoperatively, the abnormal endocrine levels were normalized, and all of the clinical symptoms and signs were ameliorated. This is an informative case of ectopic ACTH syndrome (EAS) that was the cause of hypokalemia, hypertension, metabolic alkalosis, and hypercortisolism despite its poorly specific cushingoid morphology and uncommon imaging findings. Therefore, we recommend that clinicians investigate any possible lesion as a potential source of EAS.
Highlights
The differential diagnosis and proper management of adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome is one of the most intriguing challenges for endocrinologists [1]
Most cases of ACTH-dependent Cushing syndrome are caused by corticotroph pituitary adenomas (90%), while ectopic ACTH production occurs in approximately 10% of cases [2]
Ectopic ACTH syndrome (EAS) is defined as endogenous hypercortisolism caused by ACTH-secreting non-pituitary solid tumors, most of which originate in the chest cavity [3, 4]
Summary
The differential diagnosis and proper management of adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome is one of the most intriguing challenges for endocrinologists [1]. Ectopic ACTH syndrome (EAS) is defined as endogenous hypercortisolism caused by ACTH-secreting non-pituitary solid tumors, most of which originate in the chest cavity [3, 4]. The tumor might be very difficult to identify in instances of occult EAS because the deteriorate features of hypercortisolism can be an obstacle for further evaluation [7]. We report a very rare case of EAS stemming from a peripheral lung lesion that had remained unchanged for 3 years and that was diagnosed as a small pulmonary carcinoid tumor adjacent to aspergilloma. The blood gas analysis was indicative of metabolic alkalosis with a pH of 7.628 and HCO3 level of 46.1 mmol/L. To differentiate Cushing’s disease from ectopic ACTH secretion, pituitary magnetic resonance imaging (MRI) was performed but revealed no lesion. To localize the source of the ectopic ACTH, radiographic investigations were performed
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