Juvenile psoriatic arthritis with nail psoriasis in the absence of cutaneous lesions

A 4-year-old white boy without a significant family history had morning sti ffness and painful swelling of his left knee and ankle, right elbow, and do rsolumbar region of 2 months' evolution. The following laboratory studies w ere within normal limits: complete blood cell count, C-reactive protein (CR P), latex, antistreptolysin, and antinuclear antibodies. Rheumatoid factor was negative and an increase in the erythrocyte sedimentation rate (ESR) wa s detected (56 mm/h). The pediatric department made an initial diagnosis of juvenile rheumatoid arthritis, and treatment with acetylsalicylic acid at 100 mg/kg/day and naproxen at 10 mg/kg/day was started. A thick, yellowish toenail was diagnosed as onychomycosis. No mycologic investigations were pe rformed. Intermittent episodes of painful arthritis of different joints were present . The radiographic features of the peripheral joints included: narrow joint spaces, articular erosions, soft tissue swelling, and diffuse bony deminer alization. Characteristic bilateral sacroiliitis and a swollen tendon sheat h on the left ankle were detected. At 11 years of age the nail changes had extended to five other toenails and to four fingernails, were yellow-brown in color, and showed marked subungu al hyperkeratosis (Figs 1, 2). The rest of the nails showed significant nai l pitting. Trials of griseofulvin alternated with itraconazole in an irregu lar form for five consecutive years resulted in no clinical improvement, wh ich prompted a consultation to our dermatology department. On three differe nt occasions, KOH nail specimens were negative for fungus, but the presence of parakeratotic cells aroused the suspicion of psoriasis. A complete phys ical examination was negative for psoriatic skin lesions. A nail bed biopsy specimen was characteristic of nail psoriasis (Fig. 3). The following human leukocyte antigens (HLAs) were positive: A9, A10, B12, B27, Cw1, Bw4, DR6, DR7, DQ1, DQ2, and DR53. A diagnosis of juvenile psoriatic arthritis associated with nail psoriasis was made. Toenail involvement became so painful that walking became very di fficult. Occlusive 40% urea in vaseline applied to the affected toenails fo r 48 h resulted in significant improvement. Currently, the patient is 20 years old with nail involvement, but no psoria tic skin lesions have ever been observed.