This particular case shows it is possible to have psoriatic arthritis and psoriatic nail changes without psoriasis of the skin. Fortunately, the patient did not have an adverse reaction to the itraconazole prescribed for the incorrectly diagnosed onychomycosis.
It is debatable whether fungal cultures are needed before prescribing oral antifungal agents for onychomycosis. This was 1 case in which the nail findings may have steered the clinician toward getting a nail scraping for microscopic analysis using potassium hydroxide or a fungal culture. Negative findings would have spared the patient the treatment with an expensive agent with known liver toxicity.
The onset of pain, swelling, and tenderness of the DIP joint of the affected nail helped to make the diagnosis. It is the finger joint most commonly affected by psoriatic arthritis.
Treatment of psoriasis of the nails
There is no good treatment for psoriasis of the nails. Treatment regimens that have been studied include injection of steroids into the nail matrix and use of topical retinoids. Intralesional steroid injections are very painful, and the results are not adequate to recommend this treatment.
A study of topical retinoid tazorotene showed some promise.3 The study size was small, however, and the measured change was not great. But for patients desperately looking for help for psoriatic nail changes, the topical treatment may be worth a try.
Figure 3 shows a different patient with an interesting connection between involvement of psoriatic arthritis in the finger and accompanying nail changes. This man had psoriatic plaques over his fingers and a severely swollen DIP joint of the middle finger with significant accompanying nail changes. The inflammatory reaction in the DIP joint is accompanied by abnormal changes in the nail matrix, producing a psoriatic nail on the same finger.
FIGURE 3
Another patient’s hand, with psoriatic plaques and swollen distal interphalangeal joint.
