Endocrine Abstracts

Introduction: A form of ACTH-dependent Cushing syndrome is an ectopic production of ACTH. The aetiology can by benign lesion or a malignant non-pituitary tumor, which is more common. The prevalence of endogenous Cushing syndrome is 1 in 26 000. Ectopic ACTH secretion is responsible for 7–15% of the cases. Principal position of the ACTH-producing tumor is in lungs – a bronchial endocrine tumor and small cell lung cancer. Small peripheral bronchial carcinoids can easily be missed by CT examination of the chest. MRI and octreotide scintigraphy are of little value to identify these small forms of bronchial carcinoid (33–44% of tumors are missed).

Case report: We report a case of ectopic ACTH syndrome caused by a lung carcinoma in a 37-year-old male patient with clinical features of Cushing syndrome, serious hypokalemia and hypercortisolismu. Clinical investigation confirmed the diagnosis of ectopic ACTH production. We performed 2 mg dexamethasone suppression test which showed no suppression. In 8 mg dexamethasone suppression test was only parcial suppression present. Sampling from sinus petrosus inferior showed an ectopic cause of hypercortisolism. PET CT scan of the chest showed a solitary deposit (14 mm) in upper right lobe of lungs. The deposition showed only a slight metabolic activity. Consequent thoracotomy and histological examination of the tissue confirmed a primary lung carcinoma. After the extirpation was detraction syndrome present. The treatment consisted of glucocorticoids supplementation with sequential reduction of the dose. Clinical and laboratory features of Cushing syndrome detracted as well. The time period from the first diagnostic tests to the surgical extirpation of the tumor was very short (<4 months).

Conclusions: Localisation of the source of ectopic ACTH can be problematic. Surgery of tumour is normally curative, but it should be performed as soon as possible. Very rapid diagnosis followed by curative surgery prevented the onset of complications connected with hypercortisolemia and also lung cancer.