Case Study : Dermatology
89. Plaque psoriasis
89. Rash on abdomen
A 25-year-old man presented to his family physician (FP) with a new rash on his abdomen.
He said that it was itchy, but not painful.
The FP noted an annular pattern and suspected tinea corporis, but a potassium hydroxide (KOH) preparation came back negative.
Searching for more clues, the FP found pitting in many of the patient’s fingernails.
The patient denied any joint pain or morning stiffness.
He also denied using tobacco and said he rarely drank alcohol; he was, however, overweight.
Based on the negative KOH and the nail pits, the FP made a diagnosis of plaque psoriasis.
This condition can present in an annular pattern resembling tinea corporis.
Otherwise, a 4-mm punch biopsy of the area with erythema and scale would confirm the diagnosis.
Plaque psoriasis is typically treated using a mid- to high-potency topical steroid.
Although repeated use of steroids in cases of atopic dermatitis can lead to skin atrophy, this is less common when treating psoriasis.
If skin atrophy is still a concern, an alternative to topical steroids is a topical vitamin D preparation.
Vitamin D preparations are typically more expensive than steroids and require prior authorization, but there is one generic preparation (calcipotriene) that is more affordable than its brand-name counterparts.
Another nonsystemic treatment to consider when treating plaque psoriasis without psoriatic arthritis is narrow-band ultraviolet B therapy.
One risk factor for psoriasis is being overweight.
In this case, the FP counseled the patient on weight loss.
The FP then prescribed 0.1% triamcinolone ointment to be applied twice daily (especially after bathing).
At a follow-up appointment a month later, there was about 70% clearance of the lesions.
For the stubborn areas, the FP prescribed a higher-potency steroid, 0.05% clobetasol ointment, to be applied twice daily.
As the cost of clobetasol has risen over the past 2 years, alternatives that may be covered by insurance include augmented betamethasone and halobetasol.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R. Psoriasis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013: 878-895.
Calciprotiene is N/A in Ireland.
Vid D skin preparations are available in Ireland OTC (e.g. Vit D3 1000U intense moisture from Now Solutions)
Clobetasol is available in Ireland as Dermovate.
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