Hi and thanks for posting

Perianal abscesses can sometimes take a very long time to heal. There may be a few reasons for this , which is why an MRI may show if there is a fistula which is preventing healing. Sometimes, if an abscess was drained and not excised there may still also be some of the abscess still present, which means the source of infection is still there. 

However, no one sometimes really knows without further tests so it's good that your husband has been referred for these.

I'm not sure whether the past testicular cancer could be a reason for not healing , although it sounds unlikely. If there aren't any other symptoms , a cancer like lymphoma would also perhaps be less likely, though I can't say.

I imagine he may have had some bloods done to also include a check for diabetes, as this too can sometimes prevent healing.

I hope things start to clear up soon for your husband as I can imagine you must be all feeling pretty fed up with things going on for so long.

All the best

Wanda