Abstract Introduction Eosinophilic Granulomatosis with Polyangiitis (EGPA) is a rare, small- to medium-vessel ANCA-associated vasculitis characterized by asthma, eosinophilia, and multisystem involvement. While histopathologic confirmation remains the diagnostic gold standard, clinical diagnosis may be necessary when biopsy is not feasible or safe. Differentiating EGPA from infectious, allergic, or drug-related eosinophilia can be particularly challenging in immunocompromised patients such as those with HIV. We present a case of probable EGPA in an HIV-positive woman with severe asthma and myositis, illustrating the complexities of diagnosis and management in this population. Case Presentation A 62-year-old woman with severe persistent asthma, recurrent urticaria, HIV (diagnosed 1997, on ART), IgG kappa MGUS, and prior tuberculosis presented with progressive right arm pain, redness, and swelling. She also reported a sharp, persistent right temporal headache radiating to the neck and erythematous blotching on both thighs one day prior to admission. Over the preceding year, she developed moderate asthma initially attributed to post-COVID inflammation, requiring multiple steroid courses despite inhaler therapy. She also experienced recurrent pruritic eruptions that resolved with steroids but were unresponsive to antibiotics. Allergy and Rheumatology evaluations were ongoing for recurrent eosinophilia and systemic symptoms. On admission, she was tachycardic but hemodynamically stable. Labs revealed leukocytosis, eosinophilia, and elevated CRP, ESR, IgE, and rheumatoid factor. ANA and ANCA panels were negative. Physical exam noted non-blanching erythematous plaques on both thighs and right elbow swelling. Imaging demonstrated right forearm and elbow myositis, chronic sinus inflammation, and bronchiectasis with peribronchial thickening. Cardiac MRI was normal. She was treated with IV methylprednisolone 60 mg daily with rapid improvement in pain and rash. She was discharged on an oral steroid taper, Bactrim prophylaxis, and mepolizumab for presumed EGPA based on ACR/EULAR classification criteria. Biopsy was deferred given high clinical suspicion and exclusion of alternative etiologies. Discussion This case highlights the diagnostic and therapeutic challenges of suspected EGPA in an HIV-positive patient. The overlap between allergic, infectious, and inflammatory processes complicated recognition of vasculitis. Despite the absence of histologic confirmation, the constellation of asthma, eosinophilia, skin and muscle involvement, and steroid responsiveness supported a probable diagnosis. Importantly, the use of anti-IL-5 therapy (mepolizumab) reflects an evolving steroid-sparing strategy for non-severe EGPA, particularly relevant in patients at risk for steroid toxicity or immunosuppression-related complications. This case emphasizes the need for heightened clinical suspicion and multidisciplinary collaboration in identifying and managing EGPA in complex immunologic settings. This abstract is funded by: None
B L Freedman (Fri,) studied this question.