Co Existence of a Corticotroph Adenoma and a Multifunctional Pituitary Cyst

Abstract

The co-existence of a corticotroph adenoma and a pituitary cyst is very unusual. We present the case of a 50-year-old female who presented with a Cushingoid phenotype, severe hypokalaemia, hyperglycaemia and hypertension. Urinary free cortisol was markedly elevated at 50 fold. ACTH levels were elevated at 121.4 pg/ml. She failed both the low and high dose dexamethasone suppression tests. The CRF test did not show a satisfactory rise in ACTH levels but the Inferior petrosal sinus sampling revealed a central to peripheral ACTH gradient highly suggestive of Pituitary dependant Cushing’s. MRI pituitary revealed a large cystic lesion with a small solid component. Computed Tomography (CT) of thorax abdomen and pelvis was normal. A trans-sphenoidal hypophysectomy was performed, during which a fine needle aspiration of the intra-cystic fluid was obtained. This showed markedly elevated pituitary hormone levels of ACTH (1399pg/ml), prolactin (353,084mIU/L), TSH (217IU/L) FSH (205mIU/ml) and GH (519 ng/ml) consistent with a multifunctional pituitary cyst. Neuropathology of the solid component confirmed a corticotroph adenoma. Post-operative am cortisol levels were persistently suppressed to less than 50 nmol/l with marked improvement in clinical features. This case highlights the challenges in the work up of Cushing’s syndrome and the limitations of diagnostic tests. The coexistence of a corticotroph adenoma and a multifunctional pituitary cyst is very unusual and to our knowledge has not been reported before.