Abstract
BACKGROUND: Ectopic adrenocorticotropic hormone secretion syndrome occurs in 10% of all patients with adrenocorticotropic-hormone-dependent hypercortisolism. It is usually associated with overt malignancies or with occult and indolent tumors. This study aims to confirm the source of ectopic adrenocorticotropic hormone in four patients with ectopic Cushing's syndrome over time. CASE PRESENTATION: A 38-year-old Iranian man with Cushing's syndrome underwent bilateral adrenalectomy since the source of ectopic adrenocorticotropic hormone secretion was not localized and pituitary imaging was normal. A whole-body scan revealed a right-lung tumoral mass with mediastinal lymph node metastasis. The mass was assumed a lung carcinoid tumor with mediastinal adenopathy. Right-lung mid-zone lobectomy and mediastinal lymphadenectomy were done. In a 47-year-old Iranian man with Cushing's syndrome, whole-body computed tomography scan revealed a pulmonary nodule in the posterior segment of the left lower lobe of the lung. The third case was a 25-year-old Iranian man who presented with symptoms and signs of Cushing's syndrome. Pituitary magnetic resonance imaging revealed a microadenoma 5 × 9 mm. Whole-body scan showed abnormal focal somatostatin receptors analog avid lesion in the posterior aspect of inferior third of right lung, highly suggestive of ectopic adrenocorticotropic-hormone-producing tumor. The last case was a 43-year-old Iranian woman with Marfan syndrome with a history of mitral and aortic valve replacement and chronic dissection of the aorta, who presented with symptoms and signs of Cushing's syndrome. She underwent bilateral adrenalectomy 1 year later owing to failure to locate ectopic adrenocorticotropic hormone syndrome. Whole-body scan showed abnormally increased radiotracer uptake in the midline of the skull base and posterior aspect of the middle zone of left hemithorax and bed of left lobe of thyroid. CONCLUSION: The clinical spectrum of ectopic adrenocorticotropic hormone secretion syndrome is wide, and distinguishing Cushing's disease from ectopic adrenocorticotropic hormone secretion syndrome is difficult. Initial failure to identify a tumor is common. Pulmonary carcinoid or occult source of ectopic adrenocorticotropic hormone secretion syndrome is usually the cause. In occult cases of ectopic adrenocorticotropic hormone in which the tumor cannot be localized, serial follow-up with serial computed tomography, magnetic resonance imaging, or scintigraphy is recommended for several years until the tumor can be localized and treated.