I've been looking into the databooks and past chapters because of the "10 year ago" comment Kisame made in the previous chapter.
What I've found is pretty strange, but the reason that I added the question mark is that I've found that there is no inherent paradox, but you have to make several pretty strange conjectures to make it all work.
Here's the facts:
- Itachi became a chuuin at the age of 10 (databook 2, pg 41)
- Sasuke's flashback begins when Itachi is around 10 or 11, this can be placed by the fact that Hugaku said that "you've gotten this far in half a year since you've become a chunin" (chapter 220, pg~15).
- Sasuke's flashback extends to sometime after Itachi became an Anbu captain, which places Itachi at 13 or older (databook 2, pg 37).
- Orochimaru's flashback is unlinked in time, but both he and Itachi were in Akatsuki, as always, it's difficult to determine Itachi's age.
- Kisame's statement means that both Itachi and Orochimaru were members sometime at or before 10 years ago.
- Orochimaru said that he left Akatsuki because he could not obtain Itachi's body
Adding all this together, it means that Itachi has been a member of Akatsuki even when he was a chunin...before he gained the MS and before he became a missing nin...somehow being physically present at at least one team meeting...despite the fact that he's a 10 year old...
Or Kishimoto messed up somewhere and this is actually supposed to make sense.