Pituitary adenoma detected on FDG positron emission tomography in a patient with mucosa-associated lymphoid tissue lymphoma.

A 52-year-old woman with a history of treated non-Hodgkin's lymphoma, B-cell type, was examined for a right eyelid mass proved on excision to be a mucosa-associated lymphoid tissue lymphoma. She was referred for F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging of the whole body, including the brain, to identify the possible presence or recurrence of lymphoma. The FDG-PET images revealed focal marked FDG uptake in the pituitary gland but no evidence of abnormal metabolic sites in the rest of the body, including the orbital regions. Magnetic resonance imaging and computed tomography confirmed a 1.8 x 1.5 cm intrasellar mass. Surgery was performed, and histologic examination revealed a nonfunctional adenoma that was negative for leukocyte common antigen staining, an antigen that is positive in lymphoma but negative in pituitary adenoma. This case provides evidence for avid uptake of FDG on PET imaging of pituitary adenomas.