Psoriasiform drug eruption due to abatacept.

A 59-year-old woman presented with a 4-month history of erythematous plaques on her palms and extremities. The patient had a long-term history of using methotrexate (8 mg/week) and oral prednisolone (10 mg/day) as therapy for RA, which had been diagnosed at the age of 37. Laboratory findings were as follows: white blood cell count 10,300 /μl; C-reactive protein 1.27 mg/dl (normal < 0.3 mg/dl); anti-nuclear antibody × 40; rheumatoid factor 68 IU/ml (normal < 20 IU/ml); rheumatoid arthritis particle agglutination × 320 (normal < × 40); autoantibody to galactose-deficient IgG 74.9 AU/ml (normal < 6 AU/ml); and matrix metalloproteinase-3 195 ng/ml (normal 17.3–59.1 ng/ ml). Three years previously, the patient had enrolled in a clinical trial to study the effects of abatacept (750 mg/day, once every 4 weeks). The patient’s clinical symptoms of RA were well-controlled with abatacept, and thus oral prednisolone was ceased approximately 4 months before her admission to our department. Physical examination revealed that erythematous plaques of various sizes with scales were present on the patient’s extremities, palms and soles (Fig. 1). Microscopically, there was a parakeratotic hyperkeratosis with irregular acanthosis and a localized thinning of the granular layer (Fig. 2A). Cellular infiltrate comprising mononuclear cells and a few neutrophils was found around perivascular areas in the upper dermis. Inflammatory cells infiltrated into the epidermis and an accumulation of neutrophils in the cornified layer was found (Fig. 2B). The patient had no medical or family history of psoriasis. The eruptions were initially resistant to topical corticosteroids, but gradually improved within a few weeks. Skin patch-testing with abatacept (10% and 20%) was negative. After the remission of skin symptoms, abatacept was re-administered, resulting in the recurrence of skin symptoms within a few days. The patient is being controlled with reduced doses of abatacept (less than 500 mg/day) together with occasional use of topical corticosteroids.