DISCUSSION
Psoriasis is extremely common, affecting about 3% of the white population in this country, and is one of a handful of conditions that manifest with the Koebner phenomenon. This means that any trauma (ie, scrapes, burns, scratches, or cuts) can trigger or extend the condition. In this case, the hot wax was likely the culprit.
The patient’s primary care provider, it turns out, was treating the elbow and knee rashes with antifungal creams (to no avail). He hadn’t made the connection between her various skin problems. It was the acute manifestation in the ear that prompted a broader assessment of the patient’s condition—proving the maxim that to find a diagnosis, you have to look for it.
Given its mild nature, this patient’s condition was easily treated with topical steroids and vitamin D-derived cream (calcipotriene). She was advised of the need to avoid exacerbating factors, such as smoking, obesity, excess alcohol intake, and stress.
There is the possibility of the disease worsening despite treatment. The patient also has about a 25% chance of developing psoriatic arthropathy. For these reasons, she will need to be followed by dermatology.
TAKE-HOME LEARNING POINTS
- Psoriasis, though very common, does not always manifest in its typical form.
- Any trauma (ie, burn, scrape, or cut) can trigger preexisting psoriasis, a response called the Koebner phenomenon.
- Several other conditions—including lichen planus, warts, and molluscum—can exhibit this same phenomenon.
- When psoriasis is suspected, potential corroboratory sites of involvement (eg, knees, elbows, nails, and scalp) should be examined. Biopsy is often needed to confirm the diagnosis.