Human papilloma virus: differentiating new primary lung cancer versus metastatic disease from previous head and neck squamous cell carcinoma.

Distinguishing new primary lung tumours from lung metastasis in patients with head and neck squamous cell carcinoma (SCC) is a challenging clinical problem. Histological examination is not always able to distinguish between these scenarios as SCC is common in both sites. Here the authors present a case of metachronous cancers of the head and neck and lung in which human papilloma virus testing was proposed as a mechanism to distinguish primary from metastatic carcinoma.