Dual bronchial carcinoids and Cushing's syndrome with a paradoxical response to dexamethasone and a false positive outcome of inferior petrosal sinus sampling

Abstract

This unique case with dual bronchial carcinoids inducing hypercortisolism illustrates the problems with identifying the source of ACTH in CS. Possibly, an abnormal regulation of ACTH production in response to dexamethasone, or steroid-induced tumor necrosis, explains the paradoxical outcome at dexamethasone suppression, and the false positive result at BIPSS reflects an unusual sensitivity of the pituitary corticotrophs to CRH in this patient. The work-up illustrates the great value of (11)C-5-hydroxytryptophan-PET as a diagnostic procedure when other investigations have produced ambiguous results.