The story
By surface analysis, vesiculo- + pustule, diachronically, probably postdating and influenced by the adjective vesiculopustular.
Etymology from Wiktionary, CC BY-SA 4.0.
vesiculopustule
Today it means: Any skin lesion that may be a vesicle (blister), a pustule (pus-filled bump), or one of those in the process of turning into the other. Full definition →