CATETERIZAÇÃO DE SEIO PETROSO INFERIOR NO DIAGNÓSTICO DE SÍNDROME DE CUSHING

Introduction : 15% of ACTH-dependent Cushing´s syndrome is due to ectopic ACTH-secreting tumor. Radiological and biochemical techniques have been developed to assist distinguish the source of the hormone: ectopic or pituitary gland. Objective : Case report of an ACTH-dependent Cushing´s syndrome whose diagnostic definition was conducted by bilateral inferior petrosal sinus sampling. Case Report: A 47 years old female, presenting with amenorrhea, weight gain, weakness, hypertension, osteoporosis, mood disorder. On examination, moon facies, dorsal hump, abdominal purple striae 1.5 cm of width, lower limb edema. Laboratory findings demonstrated ACTH-dependent hypercortisolism. Suppression test with dexamethasone 16 mg suggested ectopic ACTH production. However, imaging did not detect lesions in the CNS or elsewhere responsible for hormone excess. The patient was referred to another service to perform inferior petrosal sinus sampling, which showed no gradient between the ACTH levels measured close to the gland compared to the periphery, confirming the ectopic source of ACTH. New imaging tests showed tumor in the thymus. Patient underwent thoracoscopy with excision of the lesion and was discharged on the 10th postoperative with normalization of cortisol and ACTH. Conclusion: The bilateral inferior petrosal sinus sampling is the test that provides greater sensitivity and specificity in differentiating pituitary and ectopic ACTH production. Once the initial imaging tests showed no tumor, this test was instrumental in confirming the etiology of ectopic ACTH, which led to new research and, consequently, diagnosis and treatment.