A case of nail psoriasis-associated psoriatic arthritis successfully treated with adalimumab.

We report on a case of psoriatic arthritis associated with nail psoriasis that was successfully treated with adalimumab. A 51-year-old Japanese woman presented with joint swelling and pain. She had noticed fingernail deformity five years previously. Swelling and pain of the 2nd and 4th distal interphalangeal (DIP) joints of the left hand had occurred about one year earlier, and had worsened three months before she attended our hospital for assessment. On examination, there was swelling and tenderness of the DIP joints of both hands. There were multiple hyperkeratotic punctate depressions on the nail plates of both hands, as well as scales and onycholysis with shortening of the nails (Figure 1), but her trunk and limbs showed no changes specific to psoriasis. Laboratory tests revealed elevation of C-reactive protein (CRP) to 1.13 mg/dl and erythrocyte sedimentation rate to 38 mm/h. However, rheumatic antibodies were negative, including antinuclear antibodies, rheumatoid factor, and anti-cyclic citrullinated peptide antibodies. Her human leukocyte antigen (HLA) status was A2, A26, B39, and B61. A plain X-ray film of the fingers revealed erosion and narrowing of the DIP joints of both hands. A diagnosis of psoriatic arthritis (PsA) associated with nail psoriasis was made from these joint and nail findings. Oral methotrexate (MTX) was started at 4 mg/ week (maximum dose: 10 mg/week) for her arthritis. Although her joint symptoms improved temporally, nail symptoms did not. CRP also decreased, but it increased again after 16 months. Recurrent synovitis was diagnosed and treatment with adalimumab (40 mg biweekly) was started. CRP improved rapidly, and her nail lesions resolved completely after five months of adalimumab therapy (Figure 2). Currently, inflammation is suppressed and her nail deformity has not recurred. PsA has been reported to affect from 5% to 42% of patients with psoriasis (1,2). Involvement of the nails is more frequent in patients with PsA than in those without PsA, and nail lesions with or without other skin lesions have been observed in about 80% of patients with PsA (8). However, there has only been