Salmon-pink skin rashes in adult-onset Still's disease

An otherwise healthy 21-year-old man visited a neighborhood clinic for evaluation of pharyngeal pain, arthralgia, and nocturnal fever that had begun the previous day. The arthralgia and pharyngeal pain had appeared in conjunction with the fever. The symptoms remained after administration of levofloxacin and cefditoren pivoxil. One week later, he was hospitalized because the symptoms did not improve. Two weeks after hospitalization, he had developed left inguinal pain, salmon-pink skin rashes, and >10-kg weight loss. His-family history and allergic history, including atopic dermatitis, were unremarkable. Physical examination revealed facial redness, stomatitis, and salmon-pink skin rashes from the trunk to the limbs (Figs. 1A–C). The skin rashes were characterized by pruritus, diurnal variation, and no Köbner phenomenon but showed nocturnal expansion along with the fever. The patient had mild liver dysfunction, hyperferritinemia (2097.6 ng/mL; reference range, 21.0–282.0 ng/mL), and leukocytosis (10,820 cells/mm³; reference range, 4000–9000 cells/mm³) with a neutrophil count of <80%; however, serum virus, autoimmune antibody, blood culture, bone marrow puncture, and fundus examinations were negative or nonspecific. Pathological findings of a skin biopsy from the salmon-pink skin rashes on his trunk were also nonspecific. The patient fulfilled three major criteria (fever, arthralgia, and skin rash) and three minor criteria (sore throat, abnormal liver function, and negative rheumatoid factor and antinuclear antibody) in the Yamaguchi classification of adult-onset Still's disease (AOSD). Oral prednisolone (40 mg/day) was initiated in accordance with the clinical practice guideline for AOSD. Two weeks later, the patient recovered with a decreased ferritin level (235.5 ng/mL). After tapering of prednisolone, the patient was discharged. However, he subsequently experienced several episodes of recurrence. After adjustment of the prednisolone dosage for more than 5 years, the patient was finally diagnosed with AOSD. He thereafter experienced no episodes of recurrence and required no prednisolone.