Skin - Epidermal Inclusion Cysts


Epidermal Inclusion Cysts

Q: I have a 5 yr 0ld female Irish setter,who has been fixed. She has been diagnosed with sebaceous cysts . There are many-some have been removed from her flanks and chest area. She has numerous around her vulva which have not been removed. They become infected and she has been treated with antibiotics many times.. The biopsy report states well-circumscribed cystic masses composed of a laminated keratin-filled spaces lined by stratified squamous epithelium. These epidermal inclusion cysts appear totally excised and the prognosis is good. Additionally, there is severe follicular keratosis....The cysts in the vulva were not removed as they are very large and would virtually eliminate her vulva. The cysts develope mostly in pressure point areas . My vet says he has never seen a dog with as many or as large. He has no true answers re meds, topical treatments, or diet changes for me . Any ideas??

A: I think that your vet has told you the truth, there may not be much you can do medically, with diet, or topical medications to prevent or treat these cysts. I think that some people have been using isotretinoin (Accutane Rx) to try to treat or prevent these cysts but I do not know how well it works.

I am not sure about the vulvar cysts. It seems possible to me that they may be a different problem just due to the location. However, it is also possible that epidermal inclusion cysts are the problem in the vulvar area as well. Sometimes fibrous tumors in the vaginal wall can interfere with urine flow, so watch carefully to be sure this doesn't become a problem.

You vet probably doesn't have this reference but it might interest you:

"Multiple (more than two thousand) epidermal inclusion cysts in a dog.", Canadian Veterinary Journal, June, 1995. The title pretty much explains the article, probably --- I don't get this journal, either, unfortunately.

Your vet may be able to consult with a veterinary dermatologist to determine if treatment with isotretinoin is right for your dog.

Good luck with this.

Epidermal Inclusion Cyst

Q: Dear Dr Mike,

I recently had a cyst removed from my 3 year old Lab (female). It was on her tail about 4 inches from the base on the underside; about the size of a "shooter" marble. She has always had it and I honestly thought it was a normal part of her tail. My Vet said it was a " dermal inclusion cyst" and she was probably born with it. He said after inspecting it that it was basically a hair ball and not cancerous. The only information I found was a human case study that referred to dermal inclusion cysts as synonymous with adamatinoma ( which is cancerous in humans). I've been unable to find any information on this type of cyst in animals and whether or not it is cancerous and/or hereditary. Can you enlighten me?


A: Melissa-

Terminology changes a lot over the years in veterinary medicine and it is sometimes hard to know exactly what one vet is referring to with a term like "dermal inclusion cyst". Currently, I can not find a reference to a lesion using that name exactly.

It is possible that your veterinarian meant to say that your dog had an epidermal inclusion cyst. These are common cystic lesions that are not cancerous. Many dogs that have these cysts will have more than one during their lifetime but that is due to a tendency to form them, rather than any one lesion actually spreading as occurs with cancer. Dermal and epidermal are pretty easy to confuse when speaking which makes me lean heavily towards this supposition but epidermal inclusion cysts do not usually contain hair and are not usually congenital lesions.

It is also possible that your vet is using an older name for a cyst now called a follicular cyst. These occur in young dogs (probably aren't congenital but can show up very early in life) and often do contain hair. They are less likely to occur in another place than an epidermal inclusion cyst.

In any case, I think your vet has probably given you straightforward advice on this. I have noticed a real tendency to use terms very differently between human and veterinary medicine, particularly in dermatology and oncology (cancer medicine), so you have to be really careful when comparing conditions in pets and people to be sure they really are the same thing.

Hope this helps.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...