Case Presentation: 24-year-old female presented with greater than one month history of sporadic rash with migratory arthralgias, fevers, and pharyngitis with lymphadenopathy. Patient first developed a sporadic, erythematous, non-pruritic maculopapular rash that would wax and wane during a trip to Mexico two months prior to presentation. Patient also began to experience diffuse migratory arthralgias, starting in her left fingers and wrist, moving to her right ankle and most prominently affecting her left knee. She was seen at a walk-in clinic and put on a short course of steroids, which slightly improved her rash and joint pain for a couple weeks. Shortly after the steroids were stopped, her symptoms returned and began to worsen with the rash spreading to her trunk, back, and all four extremities, and significant left knee pain with swelling. She then developed pharyngitis with lymphadenopathy and 102.7 fever, prompting evaluation in the emergency department. She was tachycardic and febrile on presentation. Initial workup was significant for leukocytosis, elevated inflammatory markers, normal rheumatoid factor, elevated liver enzymes, and a ferritin of 29,972. After extensive infectious workup was initiated and preliminary results came back negative, most likely diagnosis was determined to be adult onset Still’s disease. During admission the patient’s liver enzymes continued to increase while cell counts started declining and there was concern for macrophage activation syndrome. Patient was immediately started on high dose IV steroids with subsequent improvement in cell counts and overall symptoms. She was discharged on steroid taper with close follow up with rheumatology.
Discussion: Adult onset Still’s disease (AOSD) is an inflammatory disorder characterized by fevers, arthralgias, an evanescent rash, and hyperferritinemia. This can make it a challenging diagnosis as patient’s may have a variety of nonspecific symptoms. In this case, the patient’s presentation was further confounded by recent travel to Mexico, increasing the concern for infectious etiology. Keeping a high clinical suspicion for AOSD is important to prevent delay of treatment and complications. One feared and potentially fatal complication of AOSD is macrophage activation syndrome (MAS), a subtype of hemophagocytic lymphohistiocytosis. Concern for MAS is particularly high in patients with elevation in ferritin levels out of proportion to other inflammatory markers, transaminase elevation, marked elevation in D-dimer, thrombocytopenia, and/or a decreasing erythrocyte sedimentation rate despite continued elevation of C-reactive protein (2). Notable liver dysfunction and low neutrophils are both poor prognostic factors in the diagnosis of MAS, as well as low platelets, low fibrinogen, and high ferritin. Being aware of this complication is crucial as mortality rate in AOSD-associated MAS is 10-20% (1,3).
Conclusions: Being aware of AOSD and its treatment allows physicians to provide accurate, high quality care to patients presenting with these nonspecific symptoms. This also prevents delay of treatment, which could increase risk of the fatal complication of MAS. Therefore, AOSD should be considered and treatment promptly initiated if clinical suspicion is high.