[Diagnosis of ACTH-producing tumors. Can sinus petrosus catheterization be avoided?].

A 38-year-old woman with Cushing stigmata and an MRI confirmed pituitary tumour was referred for pituitary surgery. High-dose dexamethasone test had indicated ectopic focus. An additional peripheral CRH test was performed, indicating ectopic focus. To secure the diagnosis inferior petrosal sinus sampling (IPSS) was performed, also indicating ectopic tumour. Operation revealed an ACTH-producing tumour in the thorax. We conclude that IPSS is necessary when diagnosing Cushing syndrome.