High-risk mucosal human papillomavirus-associated squamous cell carcinoma of the fingers presents distinctive clinicopathological characteristics and outcomes: a bicentric retrospective study.

Background: High-risk mucosal human papillomavirus (HR-HPV) seems to play a role in cutaneous squamous cell carcinoma (cSCC), particularly in nail tumours, where genitodigital transmission has been suggested. The role of HR-HPV in nonungual cSCC of the finger needs to be clarified.

Aim: To evaluate the prevalence, clinicopathological characteristics, surrogates and outcomes of HR-HPV in cSCC of the finger.

Methods: This was an observational bicentric study including patients with an excised in situ or invasive cSCC located on the finger. Differences in HR-HPV and non-HR-HPV tumours were evaluated.

Results: Forty-five patients (45 tumours) were included. HR-HPV was detected in 33% of cases (22% HPV type 16). The mean age was lower in patients with HR-HPV than in those with non-HR-HPV (62·4 vs. 81·1 years, P = 0·001). HR-HPV tumours were smaller (10 mm vs. 15 mm, P = 0·07) and more frequently intraepidermal (60% vs. 20%, P = 0·004). The absence of elastosis (P = 0·030) and inflammation (P = 0·026) and the presence of basaloid morphology (P = 0·003) were surrogates of HR-HPV detection. Mean p16 positivity was 61% in HR-HPV and 36% in non-HR-HPV tumours (P = 0·061). Recurrence after surgery was more common in HR-HPV tumours (58% vs. 34%), although this was not statistically significant. HR-HPV was detected in 27% of the nonungual tumours.

Conclusion: HR-HPV-associated cSCC of the finger appears in younger patients, is smaller and is less infiltrative than non-HR-HPV tumours. The presence of a basaloid morphology and the absence of elastosis and inflammation could be used as markers for HR-HPV detection. The high prevalence of HR-HPV in nonungual cSCC suggests its aetiopathogenic role in these tumours.