Each anatomic region of the head and neck has physiologic variations that can mimic a primary tumor or lymph node. Many of these variations can be recognized as reflecting benign lymphoid, salivary, brown fat, and muscular activity. A few artifacts are related to computed tomography (CT) attenuation. A knowledge of tumor types and patterns of lymph node and metastatic spread helps categorize patterns as benign or malignant. The anatomic reference of CT helps solve many pitfalls. A recently introduced instrument, PET/magnetic resonance imaging, will face new pitfalls as its role in oncology is developed.