An 86-yr-old woman presented with fever of unknown origin. When laboratory
evaluation revealed partial hypopituitarism, a magnetic resonance imaging s
can of the head was performed and revealed a sellar mass consistent with a
pituitary adenoma. Only after other possible etiologies for fever were excl
uded did she undergo transsphenoidal resection of the sellar mass, which pr
oved to be a B-cell lymphoma. Primary central nervous system lymphoma of th
e pituitary region is a rare cause of a sellar mass, and this is the first
reported case of pituitary lymphoma whose presenting manifestation was feve
r of unknown origin. Several disease processes can manifest themselves as f
ever and a sellar mass, including lymphomas. In our case, only surgical bio
psy could make a diagnosis and distinguish this process from the more commo
n pituitary adenoma.