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Head and neck squamous cell carcinoma of unknown primary

Authors
Benjamin E Saltman, MD
Sue S Yom, MD, PhD, MAS
Section Editors
Marshall R Posner, MD
Bruce E Brockstein, MD
David M Brizel, MD
Marvin P Fried, MD, FACS
Deputy Editor
Michael E Ross, MD

INTRODUCTION

Head and neck squamous cell carcinoma (SCC) of unknown primary is defined as the presence of SCC in one or more lymph nodes within the head and neck region that are not solely in the supraclavicular region, without an identifiable primary tumor. While many head and neck cancer patients initially present with a neck mass, the mucosally based primary site of origin is usually identified over the course of the subsequent workup.

Thus, SCC of a truly unknown primary origin is a relatively rare entity in the head and neck region; retrospective studies suggest that it represents between 1 and 3 percent of new cases of head and neck SCC [1]. It is commonly thought that many SCC of unknown primary may represent clinically occult oropharyngeal cancers. A contemporary single institution series of 75 patients with SCC of unknown primary found that 69 (90.5 percent) were positive for human papilloma virus (HPV) by either p16 positivity or in situ hybridization [2], although some older series have reported a lower incidence [3].

The special case of isolated supraclavicular lymphadenopathy, including those of squamous cell origin, almost always originates from cancer in the skin or a primary site beneath the clavicles (ie, lung, breast, colon, prostate, esophagus, cervix, ureteral, and lymphoma primaries) [4]. These cancers are associated with a different natural history and prognosis than cancers originating from the head and neck.

The management of head and neck SCC of unknown primary is directed at cure for most patients; cervical lymphadenopathy represents disease that is locoregionally advanced but is not distantly metastatic in most patients. This is in sharp distinction to cancers of unknown primary originating from below the clavicles, for which supraclavicular adenopathy may represent incurable distant metastasis.

The diagnosis and management of patients with SCC of unknown primary presumed to originate from the head and neck are presented here. The initial evaluation of a neck mass and the general approach to neoplasms of unknown primary origin are discussed separately.

             

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Literature review current through: Nov 2016. | This topic last updated: Tue Apr 12 00:00:00 GMT+00:00 2016.
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