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Case Reports

Abstract

A 30-year-old-male with a recent diagnosis of adult-onset Still disease (AOSD), initially treated with prednisone 60mg daily, was admitted with fevers, gastrointestinal upset, myalgias, and a diffuse, erythematous eruption concerning for an AOSD flare. Despite escalation of immunosuppression with high-dose pulse glucocorticoid therapy and anakinra (IL-1 receptor antagonist), the eruption persisted and peripheral eosinophilia and transaminitis developed. Clinically, the eruption differed from the evanescent salmon-pink patches observed at the time of diagnosis. Though distal extremities showed an urticarial morphology, the truncal and subtle facial involvement revealed a progressive, confluent, morbilliform eruption. A skin biopsy demonstrated an acute lymphocyte-predominant interface dermatitis with rare eosinophils, suggestive of a hypersensitivity reaction. Given the laboratory derangements, clinical suspicion for DRESS heightened. Anakinra was the suspected culprit based on timeline of exposure and emerging reports of DRESS-like reactions in a subset of AOSD patients receiving IL-1/IL-6 inhibitor therapy. The patient was transitioned from anakinra to emapalumab (anti-interferon-gamma antibody) as maintenance therapy with subsequent resolution of the rash and normalization of laboratories. This case highlights the potential for DRESS to masquerade as an AOSD flare and the value of dermatopathology in this context to aid in the differentiation of the two entities. Prior literature on AOSD histopathology demonstrates a spectrum of inflammatory infiltrates and reaction patterns, and calls attention to a variant corresponding to persistent skin findings characterized by prominent epidermal apoptosis. Based on our illustrative case, additional studies to determine whether these atypical cutaneous eruptions of AOSD instead represent drug hypersensitivity eruptions are warranted.