Sphenoidal Ectopic ACTH-secreting Pituitary Adenoma

Ectopic pituitary adenoma is defined as adenoma that occurs outside the sella without any continuity with the normal pituitary gland [1]. Since its description for the first time in 1909 by Erdheim in the vomero-sphenoidal region, about 75 cases have been reported in literature [2-12]. Sphenoid sinus followed by the suprasellar region remains the most common site for these adenomas[6]. Prior to our case report, literature review identified only 5 cases of sphenoidal ACTH secreting adenomas with a partial or complete empty sella [6, 13, 14]. Here, we present a case of sphenoidal ectopic pituitary adenoma presenting as Cushing’s syndrome in association with a partial empty sella.

A 16-year old female presented to our endocrinology department with 4-year history of unexplained weight gain of approximately 15 kg as the primary complaint. On further questioning she gave a history of irregular menstrual cycles for the past 3 years, episodes of facial flushing and two episodes of poor wound healing. She also complained of intermittent, mild degree, non-specific headaches lasting 1-2 hours. She was diagnosed with diabetes mellitus 2 years prior to presentation and was started on oral hypoglycemics, with which her sugars were partially controlled. On examination, she had moon-like face, hirsutism, and abdominal obesity. She weighed 70 kilograms. Systemic examination and nervous system examination were unremarkable. With the above features, a clinical diagnosis of hypercortisolic state (Cushing’s syndrome) was made and further tests were directed towards confirming it and finding the possible source of cortisol hypersecretion. Her serum cortisol estimations at 8 am, 8 pm and 12 midnight revealed values of >50 µg/dl, 20.4 µg/dl and 21.4 µg/dl respectively, all elevated beyond the normal range. A low dose dexamethasone suppression (Liddle1) test showed serum cortisol to be 12 µg/dl two hours after the last dose of 0.5 mg of dexamethasone.  A late evening (4 pm) plasma ACTH level was >10 pg/ml (elevated). Further, an 8 mg Dexamethasone suppression test (administering 8 mg of dexamethasone at 11 pm and estimating serum cortisol at 8 am the next day) revealed a value of 6.2 µg/dl (suppressed by >50%, thus signifying a positive test). The above results confirmed hypercortsolic state, showed that it was ACTH dependent and suggested pituitary to be the source. As indicated, she was investigated with an MRI of brain (Fig. 1 & 2), which showed the sella to be normal in size and shape, a partial empty sella with the pituitary gland being displaced posteriorly within the sella and no