Endocrine Abstracts

Almost all cases of prolactinomas are benign intrasellar micro- or macroadenomas. Very rarely benign prolactinomas are located outside the sella and in most of these cases the tumors are located in the sphenoidal sinus.

We here report a 35 year old woman who presented to the clinic with secondary amenorrhoea and galactorrhoea. Initial laboratory testing revealed mild hyperprolactinemia between 1100 and 1600 μU/ml and hypogonadotropic hypogonadism without further pituitary insufficiency. MRI showed normal intrasellar structures but a mass (5×6×5 mm) at the pituitary stalk just below the optic chiasm. Further investigations did not show any evidence of underlying systemic disorder or malignancy.

Stereotactic biopsy was discussed but not performed due to the risk of severe side effects. Considering the most likely differential diagnosis of an inflammatory process such as hypophysitis or sarcoidosis the patient was treated with glucocorticoids for 5 month which did not have any effect on the stalk mass or the laboratory findings. Treatment was then switched to Cabergolin and only 8 weeks after initiation of the dopamine-agonistic therapy prolactin-levels were normalized, the tumor was hardly noticeable and the patient had a regular menstrual cycle again.

Due to the course of the disease under the different pharmacological approaches we diagnosed an ectopic microprolactinoma of the pituitary stalk, a rare entity which has been described twice so far.