Investigating the Reliability of Fluorodeoxyglucose 18 Positive Emission Tomography-Computed Tomography Detection of Regional Lymph Node Metastasis in Head and Neck Malignancy.

PURPOSE: This study investigated whether fluorodeoxyglucose 18 positive emission tomography (PET)-computed tomography (CT) may be relied on to direct surgical management of the neck in patients with head and neck cancer by assessing the accuracy with which it is able to detect the presence and location of regional lymph node metastasis compared with histologic examination. PATIENTS AND METHODS: This retrospective study reviewed consecutive cases of head and neck cancer in which patients received a PET-CT scan within 3 weeks of undergoing a neck dissection performed by the Ascension Macomb-Oakland oral and maxillofacial surgery residency program from July 2013 through July 2018. Neck dissection specimens were orientated by the surgeon according to neck level and submitted for histopathologic examination. These histopathologic results served as the standard reference with which preoperative PET-CT results were compared. RESULTS: A total of 156 cases were reviewed in this study, 84 of which were included for data analysis. PET-CT exhibited an overall sensitivity of 68.9% and specificity of 61.5% in detecting regional lymph node metastasis (positive predictive value, 67.4%; negative predictive value, 63.2%). PET-CT showed a sensitivity of 71.4% and specificity of 75.0% for 34 cases involving pT1 lesions (positive predictive value, 66.7%; negative predictive value, 79.0%). Of 25 true-positive PET-CT scans correctly correlating with pN+ neck specimens, 16 (64%) were inaccurate in identifying the proper levels of metastatic disease identified by histopathologic assessment. These scans flagged 44 neck levels positive for disease, 18 (41%) of which were histologically proven false positive. Of the 48 neck levels in these cases confirmed positive for metastasis by histopathologic assessment, 22 (46%) failed detection by what would otherwise be considered true-positive PET-CT scans. CONCLUSIONS: The results of this study suggest that PET-CT is unable to adequately detect the overall presence or precise location of metastatic disease in the neck and so cannot be relied on to direct surgical management of the neck in patients with head and neck cancer.

Atypical Metastasis of p16-Positive Tonsillar Squamous Cell Carcinoma to the Pleura: A Case Report.

Incidence rates and patterns of distant metastases of head and neck malignancies are well documented in the literature, such that focused management strategies are routinely practiced in anticipation of their likely behavior. Head and neck tumors are known to most commonly metastasize to the lungs, skeletal system, and liver, generally within 2 years of definitive treatment and in the context of poor locoregional control of the primary lesion. Recent studies, however, have shown that human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (SCCa) tumors display different patterns of distant metastases than those traditionally described for head and neck HPV-negative SCCa tumors. This finding has substantial implications for how patients undergoing treatment of these cancers should be surveilled after therapy. This report describes a case of p16-positive tonsillar SCCa with metastasis to a highly unusual secondary site in the pleura to show an example of the unconventional patterns of distant metastases reported for HPV-positive oropharyngeal SCCa in the recent literature. We aim to provide a more thorough understanding of this case by discussing the pathogenesis of metastatic spread to the pleura and the clinical progression generally observed in patients with secondary pleural malignancy. This report goes on to investigate how behaviors of distant metastases exhibited by HPV-positive oropharyngeal SCCa differ from those of more conventionally described head and neck HPV-negative SCCa and the implications thereof for strategies of post-treatment surveillance of these tumors going forward.