Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that you have been waiting for a response, but your requested expert isn't online which delayed your question coming up on the list for all to answer. I would like to help if you are still interested in an opinion.
I understand that you want to know the difference between feline chin acne and mites.
Feline chin acne, is technically increased sebum and plugged oil glands on her chin.
It can be a primary condition or it can be caused by a food allergy, a local reaction to exposure to plastics, or secondary to demodex mites that live in the hair follicles on her chin. In some cases it may indicate a poorly functioning immune system due to generalized poor health from chronic disease, or immune suppression from feline leukemia or feline immunodeficiency virus.
Although chin acne is more of a cosmetic thing in most cats they can get deep secondary infections so I do recommend treatment. Amazingly enough it doesn't appear to be painful to most cats.
I generally recommend topical treatment for acne.
Cleaning the affected area with Hibiclens or Pyoben shampoo once or twice daily and keeping the chin clean and dry is helpful. Hibiclens is an over the counter facial cleanser used as an acne wash for people. Pyoben is a shampoo designed for skin infections.
It flushes out the pores/hair follicles so is very helpful with feline acne too.
Just don't get it in the mouth as it can cause drooling and stomach upset.
I usually put a dab of either of these on a wet cotton ball or gauze square and clean the affected areas.
If she eats out of plastic bowls switch to glass or stainless steel.
And pay attention to the flavors of foods she's eating as some cats with food allergies/sensitivities will get acne with a particular protein, for example fish. If that's the case avoid that protein.
If this condition becomes very inflamed I will use cortisone to try and get things back to normal and sometimes oral antibiotics, but most of the time topical therapy is enough.
If it is getting severe I recommend looking for food allergies or other allergies as a reason for the flare.
I'd have to say food allergies are probably the most common trigger. It can also be a sign of a flare up of demodex mites (which tend to worsen with a suppressed immune system) so it can be a sign that internal health isn't perfect. We diagnose the mites with skin swabs and scrapings.
Fungal infections very rarely cause this condition so it wouldn't be something that I would look for immediately, but a fungal culture would be indicated if it is persistent and not improving.
If her acne doesn't clear with topical therapy, using metal or glass bowls and careful dietary control then systemic antibiotics and a skin scraping and fungal culture may be necessary.
Let me know if you have any further questions.