Images taken by HST reveal that asteroid P/2013 P5 ejects dust quite similar to several comet tails at once.
The unusual asteroid were first detected by Pan-STARRS. Even though the text present a hypothesis to this behaviour, there's yet none to fully explain the cause.

http://newsroom.ucla.edu/portal/ucla/freak...red-249275.aspx

Would it not be appropriate to refer to the asteroid as A/2013 P5?

"The nature of an object can further be indicated by an initial prefix. In particular, such prefixes should be applied in cases where comets have possibly been misdesignated as minor planets, or vice versa. If necessary, the prefix A/ would precede a comet designation that actually refers to a minor planet (or asteroid)." http://www.minorplanetcenter.net/iau/lists...Resolution.html

Per the article the 'tails' may not be generated via the same means as cometary ejecta (vaporization of volatiles), but still a lot of unknowns. Bottom line is that this is yet another example of an object which is intermediate between two more-or-less distinct classifications, so it's really a pointless exercise to argue terminology.

Objects in nature do not exist in neat classifications (which are a human thing), they exist along a continuum.

At least it would emphasize the "special" character of the object.