Pancoast Tumor as the Initial Presentation of a Metastatic Colon Adenocarcinoma

A Pancoast tumor is a rare condition, representing 3% to 5% of all lung cancers. The particular location of these lesions leads to the invasion of structures in the thoracic inlet, causing a constellation of symptoms known as Pancoast-Tobias syndrome. Diagnosis can be challenging due to their low prevalence and the possibility of being asymptomatic. Most of these tumors are non-small cell lung cancers. However, rare conditions might arise at the same location, and histologic confirmation is relevant. We report the case of a 45-year-old man admitted to the internal medicine department with a one-month history of night sweats. A full-body computed tomography (CT) scan revealed a mass on the upper lobe of the left lung, with soft tissue invasion. Histopathologic examination revealed an adenocarcinoma pattern originating from the colon. Colonoscopy showed two synchronous lesions. Hitherto, this is the second case ever described of a Pancoast tumor as metastasis of colon adenocarcinoma.