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. 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.