By Aletha Tippett MD

Understanding Pathergy and Pyoderma Gangrenosum

Pathergy is an aberration of the skin’s innate reactivity from a homeostatic reactive mode closely coupled to tissue healing to an abnormal destructive/inflammatory mode. Pathergy is not well understood and the cause is unknown. It is a diagnostic criteria for Behcet's disease and there is even a Skin Pathergy Test to help with diagnosis. Pathergy has also been reported in Sweet’s syndrome and it is a hallmark of pyoderma gangrenosum.

With pathergy, any physical energy put into a lesion can result in development of new skin lesions or aggravation of existing ones. Years ago when I was treating one of my first patients with pyoderma gangrenosum, I did not have sufficient understanding of pathergy. I knew that surgical debridement with a scalpel was not appropriate, but did not think maggot therapy would induce pathergy. The maggots did a great job of cleaning the patient’s wound, but then we were rewarded with the pathergic response of the wound enlarging. At the time the patient was not taking prednisone or an immunosuppressant. After that experience my rule was never use maggots on pyoderma gangrenosum. Along with that, while laser therapy is a frequent adjunct in my wound care, my rule was not to use laser therapy for pyoderma gangrenosum because of the infusion of energy and inherent risk of pathergy.

Treatments for Minimizing Pathergy

Now, years later, my skills in treating pyoderma gangrenosum have thankfully advanced and now cyclosporine with or without prednisone is the mainstay of my treatment. Recently we had two patients with pyoderma gangrenosum who suffered from terrible drainage and odor. Given that both these patients were taking cyclosporine, my thought was perhaps the pathergy would be counteracted, and both patients received maggot therapy with wonderful reduction in drainage and odor, and even more wonderful, no pathergic response. Neither patient was taking prednisone; one because of uncontrolled diabetes and the other, because of an allergy to prednisone.

These two pyoderma gangrenosum patients have also received laser therapy, using an NdYAG 1064nm cosmetic laser (Aerolase®, Tarrytown, NY) at 4 joules, one pass with each visit. One patient's wounds accelerated to closure and the other patient's wounds are developing sheets of epithelium and are closing rapidly. There has been no pathergic response to the laser treatment, again a testimony to the cyclosporine the patients are taking. The laser therapy has proved so far to be very beneficial in the treatment of pyoderma gangrenosum.

The take home message is be very wary of pathergy and the dangers involved with it. If the patient is taking adequate immunosuppressive medication it appears pathergy can be avoided or minimized and thereby allow some valuable treatment modalities that otherwise would not be available to be used.

About The Author
Aletha Tippett MD is a family medicine and wound care expert, founder and president of the Hope of Healing Foundation®, family physician, and international speaker on wound care.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.