Pulmonary Manifestation of Granulomatosis With Polyangiitis: A Challenging Case Presentation.

Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, is a rare and potentially life-threatening autoimmune disease characterized by antineutrophil cytoplasmic antibody (ANCA)-associated vasculature inflammation. It presents as a systemic autoimmune disease with necrotizing granulomatous inflammation and pauci-immune small vessel vasculitis. This case initially posed a diagnostic challenge due to its atypical presentation and was misdiagnosed as hypersensitivity pneumonitis. The avian precipitin screening assay was positive in our patient, which may be consistent with bird breeder's lung disease or a non-specific reactivity of the chicken antigen test. However, the presence of positive c-ANCA was pivotal for the GPA diagnosis. Here, we describe in detail the clinical manifestations, diagnostic approach, and treatment of GPA in a 54-year-old female who presented with alveolar hemorrhage, but no renal involvement. Treatment involved the use of high-dose corticosteroids to suppress the autoimmune response. Finally, we discuss the striking response of this unique form of granulomatosis with polyangiitis to corticosteroid treatment and emphasize the importance of early initiation of treatment.