[Case with double primary cancers occurring synchronously in both the lung and jejunum diagnosed according to TTF-1...

A 47-year-old man was diagnosed as having adenocarcinoma of the lung (T4N0M0) in August 2002. He received chemotherapy and radiotherapy. In June 2003, he complained of lower abdominal pain with palpable mass in the left lower abdomen. On abdominal CT, we recognized a mass measuring 50 mm, which we considered a mesenteric lymph node. As the mass gradually grew and pain increased, we performed lymph node resection. The lymph node was near by the Treitz' ligament, and a tumor measuring 30 mm was observed in the jejunum. Therefore, we performed jejunectomy. Pathological examination of the lesion demonstrated adenocarcinoma. The differential diagnosis between small intestine metastasis and primary small intestine cancer was difficult. As adenocarcinoma of the jejunum was negative for TTF-1 in immunohistochemical staining and adenocarcinoma of the lung was positive, we diagnosed this patient as having primary jejunal cancer. We report this rare case of double cancer involving the lung and jejunum.