A 76-year-old man presented with vitritis in the absence of visible fundus
lesions. Vitreal cytologic analysis revealed adenocarcinoma; immunostaining
was consistent with a pulmonary origin. This case highlights the need to e
xclude metastasis to the vitreous in a patient with an oncologic history, e
ven in the absence of visible posterior segment lesions. It also illustrate
s the utility of immunostaining to better determine the tissue of origin wh
en a metastatic lesion is encountered.