55 yr old presents with a 3 month history of cough and is found to have a 3 cm left upper lobe mass. CT scan of the chest, abdomen and pelvis is otherwise unremarkable. Physical exam is without abnormality. CT guided biopsy reveals moderately differentiated adenocarcinoma. TTF-1 is negative.
He has a history of cigarette smoking for 30 years, but quit 10 years ago. He also has a history of colorectal cancer diagnosed 2 years ago and is s/p a low anterior resection. Lymph nodes were negative at the time and he received no adjuvant chemotherapy or radiation.
Additional immunohistochemical stains reveal the cancer to be CK 7 positive, CK 20 negative, and TTF-1 positive.