Squamous cell carcinoma of the pinna: which histological features could be used to predict prognosis?

Squamous cell carcinoma (SCC) that originates in the pinna is thought to have a high risk of metastases (up to 16%) compared with under 5% for cutaneous SCC at any other site, and histological features of the primary tumour may provide evidence for further surveillance or treatment. To identify any association between histological features and the risk of metastases we made an electronic search of the histopathological records at the University Hospital Southampton NHS Foundation Trust for all patients who presented with auricular SCC from 2007-2012. Inclusion criteria included origin in the pinna, complete two-year follow up, and no history of immunosuppressive treatment. We looked for histopathological features that were thought to be relevant to metastases. We studied specimens from 192 patients, four of whom developed metastases (2%), each with involved lymph nodes. Perineural invasion and local recurrence were significantly associated with increased risk of metastases (p<0.001 and p=0.006). The overall metastatic rate was much lower than those reported in other studies, and factors other than histological features alone may explain the results. We suggest that although some histological features were significantly associated, they do not predict a high enough risk of metastatic disease to provide evidence for further surveillance or elective lymphadenopathy.