The FP suspected psoriatic arthritis in light of the nail finding (oil drop sign due to localized onycholysis), bilaterally symmetric small joint arthralgias, and morning stiffness. Given the lack of cutaneous findings, the FP ordered hand films, a rheumatoid factor test, and an erythrocyte sedimentation rate (ESR).
Most times, nail involvement coexists with cutaneous psoriasis, although the skin surrounding the affected nails need not be involved. Psoriatic nail disease without overt cutaneous disease occurs in 1% to 5% of cases.
The diagnosis of nail psoriasis is usually straightforward when characteristic nail findings coexist with cutaneous psoriasis. Nail bed psoriasis produces localized onycholysis, which often appears like a drop of oil on a piece of paper (oil drop sign).
The patient in this case was not worried about her fingernail, but the joint pain was making it difficult to type at work. The physician started her on ibuprofen with meals to treat the probable arthritis.
During a follow-up visit one week later, the patient said that her hand pain and stiffness was about 50% better. The hand films were negative, other than some signs of synovitis on the DIP joint of the involved fingernail. In addition, the rheumatoid factor was negative and the ESR was mildly elevated.
The physician counseled the patient to lose weight and to stop smoking for general health reasons, and because smoking and obesity are 2 risk factors for psoriasis. The FP referred the patient to a rheumatologist to clarify the diagnosis and consider the use of more potent medications such as methotrexate.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Mayeaux EJ. Psoriatic nails. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. The Color Atlas of Family Medicine. New York, NY: McGraw-Hill; 2009:838-841.
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