Cervical lymph node metastases of squamous cell carcinoma from an unknown primary

Cervical lymph node metastases of squamous cell carcinoma from occult primary constitute about 2-5% of all patients with carcinoma of unknown primary site (CUP). Metastases in the upper and middle neck are generally attributed to head and neck cancers, whereas the lower neck (supraclavicular area) involvement is often associated with primary malignancies below the clavicles. The diagnostic procedures include physical examination with thorough evaluation of the head and neck mucosa using fiber-optic endoscopy, biopsies from all suspicious sites or blindly from the sites of possible origin of the primary, computer tomography and/or magnetic resonance. A systematic tonsillectomy in the absence of suspicious lesions is often recommended since up to 25% of primary tumors can be detected in this site. The thoracic primary (tracheal, bronchial, lung, esophagus) has to be excluded, especially in the case of lower neck involvement. Positron emission tomography (PET) with fluoro-2-deoxy-D-glucose allows detection of primary tumor in about 25% of cases, but this procedure is still considered investigational. Therapeutic approaches include surgery (lymph node excision or neck dissection), with or without postoperative radiotherapy, radiotherapy alone and radiotherapy followed by surgery. In early stages (N1), neck dissection and radiotherapy seem to have similar efficacy, whereas more advanced cases (N2, N3) necessitate combined approaches. The extent of radiotherapy (irradiation of bilateral neck and mucosa versus ipsilateral neck radiotherapy) remains debatable. A potential benefit from extensive radiotherapy should be weighted against its acute and late morbidity and difficulties in re-irradiation in the case of subsequent primary emergence. The role of other methods, such as chemotherapy and hyperthermia, remains to be determined.