Recurrent Cushing`s syndrome with no morphological substrate after transsphenoidal pituitary adenomectomy

Abstract

Introduction: Cushing`s syndrome (CS) is caused by prolonged exposure to increased levels of endog­enous or exogenous glucocorticoids. Endogenous hypercortisolism is a rare condition which mani­fests itself with a number of specific morphological features and can lead to hypertension, osteopo­rosis and diabetes. A number of laboratory analyses and diagnostic procedures are usually required to distinguish between adrenocorticotropic hormone (ACTH)-dependent (pituitary microadenoma, hypothalamus hyperfunction, ectopic secretion of ACTH or corticotropin-releasing hormone) and ACTH-independent (adrenal tumor, macronodular adrenal hyperplasia) etiologies of CS. Materials and methods: A 53-year-old woman is presented with a typical clinical constellation of CS - centripetal obesity, muscle weakness, hypertension, moon face, facial plethora, buffalo hump, pur­ple striae and hirsutism. The laboratory tests displayed increased serum and urine concentrations of cortisol. Computed tomography scan revealed a nodule in the left adrenal gland. Contrast-en­hanced MRI showed evidence of pituitary microadenoma and transsphenoidal adenomectomy was performed. Results: High serum and urine cortisol levels persisted postoperatively while ACTH value was within the reference range. The 8-mg dexamethasone suppression test demonstrated a decrease in the morn­ing cortisol levels to 209,37 nmol/l, although not reaching the target cut-off (50 nmol/l). Data for re­current pathologies in the pituitary gland or change in the nodule size were not detected. Further ex­amination included an invasive diagnostic procedure - bilateral inferior petrosal sinus sampling (BI­PSS), which indicated elevated levels of ACTH in the right inferior petrosal sinus - 138 pg/ml (com­pared to 30,2 pg/ml in the serum). BIPSS proved the central genesis of CS. As a therapeutic opportu­nity, palliative adrenalectomy was discussed. Conclusion: CS often presents a clinical and diagnostic dilemma. BIPSS is an invasive and hard to perform specialized procedure. Although being useful for establishing the source of ACTH produc­tion, it has to be performed only in high technology centers.