More than a Polyp

Abstract

Purpose: Gastrointestinal metastasis from the lung cancer is rare and when encountered the common site of metastasis is usually to the small bowel. The diagnosis of metastasis made either on imaging or during symptomatic presentation such as bleeding or intestinal obstruction. We report a case of asymptomatic metastatic lung cancer detected as a sessile polyp on a routine colon cancer screening. A 65 year old male was followed up by his primary care physician for hypertension and hyperlipidemia. His past history was notable for recurrent diverticulitis in the past requiring sigmoid resection and a rectal polyp (tubular adenoma, low grade dysplasia) discovered 8 years ago. He was on medications for his hypertension and hyperlipidemia. He had no prior history of smoking, or family history of cancer. He was asymptomatic during the clinical visit. He underwent colon age appropriate cancer screening and a 1 cm sessile poly was found in the distal transverse colon. The biopsy results of his sessile poly showed moderately differentiated adenocarcinoma. Immunohistochemical stains were performed using antibodies directed against synaptophysin, PSA, cytokeratin 20, chromogranin, cytokeratin 7, S100, and TTF-1. The neoplastic cells showed strong cytoplasmic positive staining for cytokeratin 7 and strong nuclear staining for TTF-1. The positive TTF-1 staining virtually excluded a colorectal primary malignancy. The combination of immunostains plus histology was consistent with a metastatic non-small cell carcinoma from a pulmonary primary. The patient had no history of pulmonary symptoms such as cough, chest pain or dyspnea. He underwent a CT scan of the chest which showed multiple pulmonary nodules, largest measuring 5.5 × 3.3 cm with mediastinal lymph adenopathy. A flexible bronchoscopy was performed and biopsy from the lung confirmed the diagnosis of grade 3/4 adenocarcinoma of the lung. Later he was evaluated in oncology where a review of systems revealed occasional headache without any other neurological symptoms. His clinical examination was again unremarkable however a CT scan of the head showed multiple cystic lesions with vasogenic edema. Treatment was started with Carboplatin and Paclitaxel, but disease progression occurred on combination chemotherapy. Gastrointestinal metastasis from the lung cancer is rare, and to the best of our knowledge this is the first case report of stage IV metastatic lung presenting as sessile polyp in an asymptomatic patient.