Unknown primary carcinoma presenting as cervical lymph node metastasis accounts for approximately 5% of all head and neck malignancies. The typical presentation involves a middle-aged man with a painless neck mass that has been present for several months. Over 90% of these malignancies represent squamous cell carcinoma originating within Waldeyer's ring (lymphoid tissue of the nasopharynx, tonsil, and base of tongue). The remainder are comprised of adenocarcinoma, melanoma, and other rare histologic variants. The ability to identify the occult primary tumor is imperative because identification allows site-specific therapy and avoidance of wide-field radiation side effects. Following confirmation of metastatic cervical disease with fine-needle aspiration, all patients presenting with an unknown primary carcinoma require a thorough head and neck history and physical examination, radiographic imaging, panendoscopy with directed biopsies of Waldeyer's ring, and bilateral tonsillectomy. Positron emission tomography has proved helpful in identifying occult primary tumors of the head and neck region.
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