A Pancoast tumor is an apical tumor that is typically found in conjunction with a history of smoking tobacco. The clinical signs and symptoms may be mistaken for neurovascular compromise at the level of the superior thoracic aperture. The patient's smoking history, rapid onset of clinical signs and symptoms, and pleuritic pain can suggest an apical tumor. A Pancoast tumor can give rise to both Pancoast syndrome and Horner's syndrome. When the brachial plexus roots are involved, it will produce Pancoast syndrome; involvement of sympathetic fibers as they exit the cord at T1 and ascend to the superior cervical ganglion will produce Horner's syndrome.