The Collaborative International Dictionary of English v.0.48:

Vesication \Ves`i*ca"tion\, n. [Cf. F. v['e]sication.] (Med.)
   The process of vesicating, or of raising blisters.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vesication
    n 1: the formation of vesicles in or beneath the skin [syn:
         vesiculation, vesication, blistering]