Eosinophilic Granulomatosis With Polyangiitis (EGPA) Manifesting as Giant Cell Arteritis After Initiating Treatment With Dupilumab: An Unusual Clinical Presentation.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody (ANCA)-associated multisystemic small vessel inflammatory disease. Its diverse clinical presentation overlaps both within its own phases and with other disorders, complicating diagnosis. We present a case of a 60-year-old female who developed symptoms suggestive of giant cell arteritis (GCA) with polymyalgia rheumatica (PMR) shortly after starting treatment with dupilumab for severe rhinosinusitis. On further evaluation, the temporal artery biopsy was negative for arteritis, and the skin biopsy confirmed the diagnosis of EGPA. This case emphasizes the importance of recognizing shared symptoms and constantly reassessing vasculitis patients. Timely and accurate diagnosis is crucial for unique treatment strategies tailored for each vasculitis. This case also brings attention to the fact that some anti-asthma drugs, including dupilumab, can potentially unmask pre-existing subclinical EGPA. Although there are few documented cases of EGPA diagnosed after dupilumab treatment, this association requires further investigation, as current literature is uncertain whether it acts as a trigger versus lacking a direct impact on disease treatment.