Diagnostic Evaluation of Squamous Cell Carcinoma Metastatic to Cervical Lymph Nodes from an Unknown Head and Neck Primary Site

Objectives/hypothesis: To discuss our experience with the diagnostic evaluation in patients with squamous cell carcinomas (SCCAs) of the head and neck metastatic to the cervical lymph nodes from an unknown primary site.

Methods: Between June 1983 and December 2008, 236 patients were evaluated with lymph node biopsy, computed tomography (CT), and/or magnetic resonance imaging (MRI) of the head and neck, and panendoscopy with directed biopsies. Additional studies included fluorodeoxyglucose-single photon emission computed tomography (FDG-SPECT) in 26 patients and FDG-positron emission tomography (FDG-PET) or FDG-PET/CT in 21 patients. Seventy-nine patients underwent an ipsilateral (72) or bilateral (seven) tonsillectomy.

Results: An occult primary site was detected in 126 patients (53.4%); six patients had two synchronous primary cancers. The most common primary sites were in the tonsillar fossa (59 patients; 44.7%) and the base of tongue (58 patients; 43.9%). The primary site was found in 21 (29.2%) of the 72 patients with no suspicious findings on physical exam and/or radiographic evaluation compared with 105 (64.0%) of 164 remaining patients. Tonsillectomy revealed the primary cancer in 35 (44.3%) of 79 patients. FDG-SPECT and FDG-PET or FDG-PET/CT was the sole method of primary site detection in only one patient (2.1%) of 47 patients.

Conclusions: Diagnostic evaluation should include a thorough physical examination, CT and/or MRI of the head and neck, and panendoscopy with directed biopsies. Unilateral or bilateral tonsillectomy should be performed on patients with adequate lymphoid tonsillar tissue. FDG-PET or FDG-PET/CT should be considered for those with indeterminate findings on physical examination and/or head and neck CT and/or MRI if those sites are located outside of the oropharynx.