CD276 and pachyonychia congenita: Whilst the immune checkpoint PD-L1 (B7-H1; CD274) is infrequently expressed in PC, another member of the B7 family of immunomodulatory type 1 transmembrane glycoprotein, B7-H3 (CD276), is highly expressed in PC, among other solid tumours, and reported to be associated with worse prognosis (4–7).