The detection of unknown primary tumors in patients with cervical metastases by dual-head positron emission tomography

A dilemma may occur in relation to patients with cervical metastases appear ing as the first sign of malignancy in the head and neck region. In these p atients, the location of the involved lymph nodes may indicate the location of the primary tumor. However, in two or three per cent of the patients, t he primary tumor cannot be identified in the diagnostic workup. The aim of the present study was to investigate the possibility of identification of p rimary tumors in patients with cervical metastases of unknown origin, by th e use of 2-(fluorine-18)fluoro-deoxy-D-glucose (FDG) dual-head positron emi ssion tomography (PET). Ten consecutive patients with a cervical metastases of unknown origin were studied with FDG, using a dual-head PET camera. Aft er the injection of 185 MBq (5 mCi) of FDG, images were performed of the he ad, neck and chest. In addition, endoscopy and biopsies were carried out wi th knowledge of the PET study. In patients in whom a primary tumor could no t be identified, a follow-up of at least 6 months was used as a control. In five out of 10 patients a primary tumor was identified by FDG-PET. In one patient multiple sites of uptake were seen, and this was found to be consis tent with non-Hodgkin lymphoma. In five patients, additional sites of incre ased uptake were found, these being consistent with unknown metastatic dise ase. Finally, in six patients, the initial treatment plan was changed due t o the PET result in five of them. In one patient, the primary tumor was res ected revealing a lesion with a diameter of 6 mm. The detection of FDG in p atients with cervical metastases of unknown origin by the use of a dual-hea d PET camera is a valuable diagnostic tool in the identification of primary lesions. (C) 1999 Elsevier Science: Ltd. All rights reserved.