TTF-1 Positivity in 2 Cases of Adenocarcinoma of the Gastrointestinal Tract

Primary adenocarcinomas of the gastrointestinal tract showing a diffuse thyroid transcription factor-1 (TTF-1)-positive immunostaining are extremely uncommon and this finding in the biopsy specimen could yield to misleading diagnosis of a metastatic lung tumor. We report the clinical and pathological features of 2 cases, occurring in a 62-year-old woman and in a 66-year-old man. The first one is a gastric adenocarcinoma with liver metastasis; the other one is a gallbladder adenocarcinoma discovered during the screening for the colorectal cancer. Both the neoplasms showed a diffuse TTF-1 positivity and both the patients did not have any evidence of lung cancer. Neither a gastric adenocrcinoma with diffuse TTF-1 expression nor a TTF-1-positive gallbladder adenocarcinoma has been described before.