In older adults, 80% of firm, persistent, and enlarging neck masses are metastatic in origin The great majority of these arise from squamous cell carcinoma of the upper aerodi- gestive tract A complete head and neck examination may reveal the tumor of origin, but examination under anesthesia with direct laryngoscopy, esophagoscopy, and bron- choscopy is usually required to fully evaluate the tumor and exclude second primaries It is often helpful to obtain a cytologic diagnosis if initial head and neck examination fails to reveal the primary tumor An open biopsy should be done only when neither physical examination by an experienced clinician specializing in head and neck cancer nor FNA biopsy performed by an experienced cytopathologist yields a diagnosis In such a setting, one should strongly consider obtaining an MRI or PET scan prior to open biopsy, as these methods may yield valuable information about a possible presumed primary site or another site for FNA With the exception of papillary thyroid carcinoma, non–squamous cell metastases to the neck are infrequent While tumors that are not primary in the head or neck seldom metastasize to the cervical lymph nodes, the supraclavicular lymph nodes are quite often involved by lung, gastroesophageal, and breast tumors Infradiaphragmatic tumors, with the exception of renal cell carcinoma and testicular cancer, rarely metastasize to the neck