Endocrine Abstracts

Background: After the diagnosis of corticotropin (ACTH) dependent Cushing’s syndrome established, its cause must be determined. Cushing’s disease (CD) is caused by corticotropin (ACTH) secreting adenomas and it accounts for roughly 75-80% of all endogenous Cushing’s syndrome. These adenomas are almost always benign. Renal cell carcinoma (RCC) is the most seen kidney cancer. In this case report, a presentation of a patient who was diagnosed with concurrent CD and RCC was planned.

Case: A 40-year-old patient admitted to our hospital with complaint of abdominal pain. Abdominal MRI performed in the urology department revealed a 7.5x7 cm mass in the left kidney, which showed a close proximity to adrenal gland. Left partial nephrectomy was performed. Pathologic evaluation revealed papillary renal cell carcinoma. Tumor diameter was 6x5x4 cm. Positron emission tomography showed no pathological metabolic activity in the lymph nodes. There was no metastatic finding. She was referred to our polyclinic with the suspicion of Cushing’s syndrome. She was diabetic and she had been using oral antidiabetic drugs for 4 years. On her physical examination she had findings of Cushing’s syndrome. 1 mg dexamethasone suppression test was performed with the suspicion of Cushing syndrome. No suppression of cortisol levels was observed in the result of the test (cortisol level=17 μg/dL). Cortisol levels were also higher than the reference values in 24 hour urine cortisol test. Basal ACTH was 47 pg/mL. Other anterior pituitary hormones were normal. The patient was evaluated as CD. Magnetic resonance imaging (MRI) of the sella revealed a 14x10 mm sized adenoma. Optic chiasm was normal. The patient underwent transsphenoidal surgery. Monitoring of the patient is continued.

Conclusions: In this case ectopic ACTH syndrome should be considered in differential diagnosis. Various tumors can cause ectopic ACTH syndrome. Small cell lung carcinoma, carcinoid tumors, islet cell tumors, pheochromocytoma and medullary thyroid carcinomas are the most frequent tumors. In ectopic ACTH syndrome circulating ACTH and corticol levels are extremely high, the duration of symptoms is short and the clinical phenotype is different from CH. The ectopic ACTH syndrome was excluded because of the presence of the pituitary adenoma, the fact that the ACTH levels were not too high and the phenotypic findings of the patient were incompatible with the ectopic ACTH syndrome. This case illustrates the importance of considering differantial diagnosis between ectopik ACTH syndrome and Cushing’s disease accompanying renal cell carcinoma.