The headword is a feminine noun in the nominative (and vocative) plural; see generally LSJ s.v. flukti/s. It is first attested in Hippocrates, On humors 2.2, and occurs too in Theophrastus, On fire (fr. 3 Wimmer); however, it is reckoned to have been extracted here from the phrase flukti/des a)naze/ousai, one of the Plagues of Egypt in Exodus 9.9-10 LXX.
[1] The headword is identically glossed in the Synagoge (phi147) Photius' Lexicon (phi231 Theodoridis), and ps.-Zonaras 1814.15. This same gloss is given by Hesychius s.v. flu/ktaina (blisters); cf. phi 552 and generally LSJ s.v. [In her critical apparatus Adler reports that ms V -- misled perhaps by the headword's grammatical number -- transmits the neuter plural article ta\. Nevertheless, fu/shma (that which is blown up, distention), is a neuter singular noun; see LSJ s.v. and omicroniota 33 (gloss).]
[2] An a)/nqrac is literally a charcoal, a coal, or an ember, here a metaphor for the blistering associated with severe fevers or infections; cf. alpha 2521, alpha 2522, alpha 2523.