Abstract
Positron emission tomography–computed tomography (PET-CT) has been shown to detect unexpected synchronous malignancies in up to 4.8% of patients and has been shown to be more sensitive than conventional staging alone. Detection of an unsuspected synchronous malignancy on PET-CT will often affect both patient treatment and prognosis. This article reviews expected patterns of disease spread so that a synchronous malignancy can be more easily recognized.