BACKGROUNDAdult-onset Still's disease (AOSD) is considered rare, usually confirmed by exclusion diagnosis from other pathologies, including hematological neoplasms.
CASE REPORTFemale, 25 years old, reported urticarial skin lesions in tights and inner side of both arms with a four-month onset. One month later, she presented arthritis in the knees, shoulders, and wrists. She also mentioned hair loss, diffuse itching and sporadic fever peaks (38-38.5 °C) that evolved into a daily symptom. Regarding familiar medical conditions, her sister and mother had established diagnosis of autoimmune disease. The patient had four COVID-19 tests with negative results and underwent several empirical antimicrobial treatments. Blood tests were requested and showed anemia (hemoglobin 11.6-9.9), elevated ferritin levels (388-2,000) were detected, and leukocytes ranged from 13,100-23,100, myelocytes and metamyelocytes were present in some of the blood samples. C-reactive protein was within the reference values and the erythrocyte sedimentation rate ranged from 67-130. Antinuclear factor 1:160 with a fine speckled pattern, rheumatoid factor, anti-SSA, and anti-DNA were negative. There was no monoclonal pattern in electrophoresis of serum protein. Extensive search for infections was conducted with negative results. At this point, the main diagnostic hypothesis was Still's disease and the hematologist ruled out early-stage hematologic neoplasm. She was prescribed prednisone 60 mg, followed by methotrexate. After one week, she did not improve and started presenting new symptoms, such as back pain and dry cough. She then was hospitalized; infections were again ruled out, but a chest X-ray showed a pleural effusion that was considered a serositis and she continued presenting fever. Prednisone 40 mg was once again started with good response at this time and she was discharged 7 days later, with a reinforced suspicion of AOSD. After several treatment attempts with different disease-modifying medications, she is currently using tocilizumab, presenting good results.
CONCLUSIONThe case has proven to be challenging due to the fact that the patient had a positive ANA, which is not very common in AOSD. In addition to that, the initial ineffectiveness of the corticosteroid therapy, raised the suspicion of hematological malignancy. Nonetheless, after restarting treatment with another prednisone drug brand, the patient started showing improvements, supporting the diagnosis of stil's disease.
