Limited diagnostic value of procalcitonin in early diagnosis of adult onset Still's disease.

A 17-year-old female patient was referred to the Infectious Diseases Ward because of fever lasting for 14 days. On admission to the hospital the patient was in a generally good state, without any abnormalities on physical examination. Laboratory investigation revealed elevated inflammatory markers. Diagnostic imaging comprising chest X-ray, abdominal ultrasonography, and echocardiography showed no abnormalities. During the hospitalization, there occurred episodes of fever with skin rash and musculoskeletal pain of the lower limbs. Procalcitonin concentrations continued to increase. C-reactive protein concentrations decreased during therapy, starting from 191 mg/l. On the 23rd day of the disease, edema of the feet, ankles, and knees appeared. On the basis of the clinical picture and after excluding other possible causes of fever, the patient was diagnosed with adult onset Still's disease. The procalcitonin concentration was normalized after 5 days of steroid therapy. The patient was discharged under ambulatory rheumatologic supervision.