Simultaneous diagnosis of adult-onset Still's disease and lymphoma: A case report and systematic review of the literature.

KEY CLINICAL MESSAGE: Differentiating Adult-Onset Still's Disease (AOSD) from lymphoma is challenging. A 23-year-old female presented with polyarthralgia, fever, rash, lymphadenopathy, and abnormal labs. She met AOSD criteria and was diagnosed with non-Hodgkin lymphoma. Treatment led to improvement.

ABSTRACT: The differentiation between Adult-onset Still's Disease (AOSD) and lymphoma remains challenging in our context. The Faustrel score facilitates the simultaneous diagnosis of these conditions. A 23-year-old woman presented with chronic polyarthralgia in a febrile context. A physical examination revealed peripheral joint syndrome, a maculopapular rash on the trunk, and peripheral lymphadenopathy. Laboratory tests showed neutrophils leukocytosis, hyperferritinemia, and a glycosylated ferritin fraction of 12%. A lymph node biopsy revealed a malignant non-Hodgkin lymphoma, and the patient met the diagnostic criteria for AOSD according to Faustrel. She received corticosteroid therapy and four courses of Rituximab. After 6 months, clinical and biological improvements were noted. It is essential to consider the possibility of an association between atypical clinical presentations of lymphoma and AOSD.