During my dermatology residency, our professors loved to talk about “imitators” – the diseases that mimic other diseases and can fool the unsuspecting student. Historically, the “Great Imitator” was syphilis because it could affect so many organ systems and manifest on the skin in numerous ways. Syphilis can show up as a sore on the skin, sores in the mouth, a rash, nodules, a collapsed nasal bridge, dementia, deafness and can occur in many other forms. Sir William Osler, one of the four founding physicians of Johns Hopkins Hospital, once said “the physician who knows syphilis knows medicine.”

Nowadays, penicillin has suppressed syphilis to a great degree, and family doctors are so expert at diagnosing syphilis that it rarely makes its way to the dermatologist before being caught by someone else. Still, one of the joys of practicing medicine is making a diagnosis that is either challenging or obscure, and dermatologists across the country are ever vigilant for imitators.

There are other diseases that qualify as imitators, and for this week’s article, I thought it worth mentioning a few of the common imitators that I see in clinic. 

For the following diseases, patients often present complaining of a “skin rash,” but what they have turns out to not be rash at all or to not be skin-based.

1. Actinic pupura – This term means sun-induced bruise. Many mature patients have bruises on the backs of their hands and their forearms, and they sometimes present to clinic asking about a rash in these locations. These are actually bruises, and they occur because years of sun-damage causes skin to bruise easily. Actinic purpura is the diagnosis when bruises are occurring only on the sun-damaged dorsal hands and forearms. Actinic purpura is, in general, not a worry. If bruises occur in areas that haven’t seen the sun, then we have to worry about a different diagnosis such as low platelets, leukemias or other blood disorders.

2. Notalgia paraesthetica – Say that word ten times fast (or even just once?!). Patients present to my clinic asking about a rash on their upper back, but there is no rash at all. The skin is completely normal, but patients are itching and uncomfortable. Notalgia paraesthetica is itching of the back caused by varying amounts of arthritis or degenerative changes in the cervical or thoracic spine irritating the spinal nerves. These nerves go to the skin on the neck and back, so this neurologic problem is perceived as a skin problem. For really severe cases, nerve dulling medicines are sometimes helpful.

3. Diffuse actinic keratoses – Actinic keratoses or “AK’s” are pre-cancers. Because patients’ sun damage is often over an entire area such as the entire cheek or scalp, patients sometimes present to clinic worried about a rash that turns out to be a field of pre-cancers. Creams and light therapies (PDT) can help eliminate these growths before they turn into skin cancer.

4. Poikiloderma of Civatte – This is another false rash that comes from sun-damage. It occurs as a red-brown mottling of the skin usually on the neck that patients dislike either because of its cosmetic appearance or because it can sometimes be mildly irritated and symptomatic. Laser treatments in combination with sun protection can improve this condition.

5. Stasis dermatitis – In this case, the problem is actually a rash, but I include it on this list because it’s so often misdiagnosed. Patients come to clinic because they keep having “cellulitis” (skin infection) over and over, but they do not have a skin infection. Rather, their veins are not working, and venous reflux leads to inflammation in the skin that mimics a skin infection. True leg skin infections are usually in only one leg and stasis dermatitis often affects both legs repetitively. 

Very effective modern vein treatments (such as EVLA and ECA) are available to fix the venous system and help with leg pain, swelling or stasis dermatitis.

We hope you enjoyed learning about the Great Imitator and a few Lessor Imitators. And if you or a loved one has a spot concerning for skin cancer, vein problems or other skin issues, please consider Premier Dermatology and Mohs Surgery of Atlanta. Dr. Brent Taylor is a fellowship-trained Mohs surgeon, board-certified dermatologist and vein specialist with his practice located at the corner of North Point Parkway and Webb Bridge Rd., Alpharetta.

At Premier Dermatology and Mohs Surgery of Atlanta, it is our pleasure to meet your skin care needs. Board certified and fellowship-trained, Dr. Brent Taylor is a skin cancer, vein and aesthetic expert honored to be of service.

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