Successful treatment of unresectable recurrent cutaneous squamous cell carcinoma of the scalp with meningeal invasion with nivolumab monotherapy.

Although the number of cutaneous squamous cell carcinoma (cSCC) cases is increasing, the effectiveness of systemic therapy for the treatment of advanced cSCC is limited. Since cSCC possesses a high tumor mutation burden (TMB) compared to other cancer species, and since high TMB correlated with increased neoantigens and the efficacy of anti-PD1 antibodies (Abs) in various cancers, cSCC could be a target for anti-PD1 Abs monotherapy. In this report, we describe a case of unresectable recurrent cSCC of the scalp with meningeal invasion, but highly expressed programmed death-ligand 1 (PD-L1), treated with nivolumab monotherapy.