Intersphincteric abscess: This condition is the most likely diagnosis given the patient's symptoms of chronic anal discharge and the MRI findings showing a tract from 2 o'clock to 6 o'clock about 5 cm away from the anal orifice. Intersphincteric abscesses are characterized by their location between the internal and external anal sphincters, which can lead to chronic discharge if not properly drained.

Ischiorectal fistula: Although less likely than an intersphincteric abscess, an ischiorectal fistula could present with similar symptoms. The fistula tract could be located in a way that does not have an obvious external opening, and its position could be consistent with the MRI findings.
Levator ani abscess: This condition involves an abscess formation in the levator ani muscle and could potentially cause chronic discharge. However, it might be less common and the location might not perfectly align with the described MRI findings.

Perineal abscess: Although a perineal abscess might seem less likely given the lack of an external opening and the specific location on the MRI, it's crucial not to miss this diagnosis due to its potential for significant morbidity if left untreated. A perineal abscess could potentially extend or have a component that does not have an obvious external opening.

Prolapse piles (hemorrhoids): While prolapsed hemorrhoids can cause discomfort and discharge, they are less likely to present with the specific findings of a chronic anal discharge without an external opening and the described MRI tract. This diagnosis seems less probable given the information provided.
Other rare conditions such as rectovaginal fistulas (in females), anorectal malformations, or congenital conditions could also present with anal discharge but would be less likely given the specific scenario and MRI findings described.