An unusual case of primary pituitary abscess due to Corynebacterium pseudodiphtheriticum.

Pituitary abscesses are an uncommon cause of pituitary lesions. A 77-year-old woman presented for elective resection of a presumed non-functioning pituitary macroadenoma in the context of a progressive left-sided visual field deficit. She proceeded to trans-sphenoidal resection of the pituitary lesion, with purulent fluid found upon opening the pituitary capsule. Culture of operative samples yielded Corynebacterium pseudodiphtheriticum, susceptible to penicillin. Following debridement, treatment with 10-weeks of directed antimicrobials achieved good clinical response. This is the first reported case of primary C. pseudodiphtheriticum infection of the central nervous system, representing a rare but important differential for a slow growing pituitary lesion.