The Collaborative International Dictionary of English v.0.48:

Fistulate \Fis"tu*late\ (?; 135), v. t. & i. [Cf. L. fistulatus
   furnished with pipes.]
   To make hollow or become hollow like a fistula, or pipe.
   [Obs.] "A fistulated ulcer." --Fuller.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fistulate
    adj 1: hollow and tube-shaped like a reed [syn: fistular,
           fistulate, fistulous]