OBJECTIVE: To discuss a case of pituitary abscess presenting with amenorrhea and diabetes insipidus, and to enumerate the differential diagnosis for this conditionSIGNIFICANCE: By presenting this case, the author aims to increase awareness regarding the possibility of infectious causes of pituitary masses, thereby prompting early recognition and treatment of similar casesCASE REPORT: This is the case of a 42-year old woman admitted due to severe generalized headache, amenorrhea and polyuria of three months duration, preceded by a one-month history of remittent fever. Physical examination was normal except for bitemporal hemianopsiaLABORATORY TEST RESULTS: On admission, she had mild anemia, hypernatremia with elevated serum osmolality, and failure to concentrate urine. Hormonal examinations showed normal thyroxine and growth hormone levels, low basal serum cortisol, and elevated prolactin levels. Cranial CT scan showed widening of the sella turcica with a homogenous, isodense, slightly enhancing focus in the sellar and suprasellar area.COURSE: Initial considerations were chiasmatic glioma versus a pituitary adenoma. Transphenoidal surgery was done and intraoperatively, purulent fluid was noted. Aspirate gram stain showed 1-2 white blood cells per high power field but with no growth on culture. Subsequently, vision was fully restored but prolactin levels continued to be slightly elevated. Basal cortisol and urine specific gravity were persistently low. Repeat CT scan showed disappearance of the pituitary mass. Six months after the operation, the patient was able to go back to work but continues to take steroids and carbamazepine for the diabetes insipidus.REVIEW OF LITERATURE: There are about 100 cases of pituitary abscess in literature mimicking pituitary adenoma and presenting with headaches, amenorrhea, visual field cuts, hypopituitarism, fever and meningitis. As in this case, the abscess is frequently sterile. Pituitary abscess should be considered in patients with a primary diagnosis of pituitary adenoma with accompanying signs and symptoms suggestive of an infection. (Author)