How to recognize sinus tracts, keratinous cysts
Dermatology Times editorial advisor, Dr. Elaine Siegfried continues her discussion with Jim Leyden, M.D., emeritus professor of dermatology at the University of Pennsylvania about the art and science of isotretinoin therapy. In part three, the two discuss distinguishing sinus tracts or keratinous cysts from nodular areas of inflammation and techniques for treating via intralesional injection.
Dr. Siegfried: A patient I saw recently had a history that was similar to this description: whatever that granulation tissue reaction is. She had horrendous crescentic bilateral scars on her cheeks. At those particular places, after she got this granulation tissue response, she had been treated with intralesional corticosteroids. All the time she was on 100 mg of isotretinoin a day. I debrided those wounds — they were really very unusual, funky flaps of skin — and the biopsy came back as epidermoid cyst. She had sinus tracts that had developed.
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She only had intralesional corticosteroids at these very persistent horrendous scars, and she had cystic acne in other places. But my gut feeling is that intralesional corticosteroids somehow might contribute to that.
In the very early days of isotretinoin, intralesional corticosteroids were a much more frequently used treatment, and I think that that particular complication of this sinus tract happened more back in those days. What are your thoughts?
Dr. Leyden: You can overdo intralesional steroids, but the first question is identifying the patient who has sinus tracts. This can be tricky. I have had patients referred to me who have failed isotretinoin, and what they have are sinus tract lesions that usually do not respond very well. Sinus tracts tend to be linear as opposed to circular, nodular lesions; they often have an angulation to them. Once you learn how to recognize them, then it is very easy to spot them. They tend to be in individuals who have other sinus tract disease or who have family members with sinus tract disease, like what we call hidradenitis or pilonidal sinus or occasionally sinus tract disease on the scalp.
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With acne you get a lot of disruption of sebaceous follicle epithelia. These patients have a tendency for epithelial repair response — to have epithelial buds migrate through the dermis and produce these linear serpentine epithelial tracts — which can become recurrently inflamed. Just like hidradenitis does not respond to isotretinoin, those types of lesions do not respond to isotretinoin treatment either.
I think intralesional steroids are very useful for sinus tracts, but if they are persistent and you just can’t get the inflammation to subside, then they actually have to be surgically removed.