The role of positron emission tomography (PET) in the management of cervical lymph nodes metastases from an unknown primary tumour.

Cervical lymph node metastases may be the initial manifestation of occult cancer. Despite a very exhaustive search, the primary site of approximately 2-10% of these tumours remain undetected. Evaluation of the patient includes: detailed physical examination of skin, upper airways (fiberoptic endoscopy), salivary glands and thyroid; fine-needle biopsy, multiple endoscopic biopsies, and imaging studies (ultrasonography, computed tomography scan or magnetic resonance imaging). Recently, positron emission tomography scan has been demonstrated to be a useful diagnostic imaging study in these patients. The records of 11 patients were reviewed. End-points were the usefulness of positron emission tomography in the detection of an unknown primary tumour and/or distant metastatic disease. In 5 patients, positron emission tomography detected a primary lesion, confirmed pathologically and revealed distant metastases in 2 patients. Two cases were false-positive and 1 false-negative. In 3 patients no primary tumour was found after 3 years follow-up. In conclusion, positron emission tomography was not of any significant advantage in detecting occult primary tumour vs. computed tomography scan or magnetic resonance imaging. Positron emission tomography, as "ab initio" total body examination, is important in detection of unsuspected distant diseases.