Xeroderma pigmentosum complementation group B (XPB) is an extremely rare subtype of xeroderma pigmentosum (XP; see this term), a rare photodermatosis predisposing to skin cancers. The disease is Xeroderma pigmentosum complementation group B (Orphanet rare-disease nomenclature id Orphanet_276252). Also known as: XPB.