Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis
(WG), is a multisystem autoimmune disease of unknown etiology often misdiagnosed as pneumonia.
The hallmark features include necrotizing granulomatous inflammation and pauci-immune
vasculitis in small and medium-sized blood vessels. We described a 15-year-old female with a history
of six months of acne-like facial and peri-auricular lesions. She had received conventional
treatment for acne (antibiotics + topical corticosteroid) with no response. She also had a history of
chronic coughs, which always diagnosed and treated as sinusitis. In addition, she had a history of
frequent dysuria, which always diagnosed and treated as a urinary tract infection. Given the history,
with suspicion of a multi-systemic disease such as vasculitis; we performed some diagnostic
laboratory and radiologic tests in order to rule out the possible etiologies. The results were positive
for cytoplasmic anti-neutrophil cytoplasmic antibody (C-ANCA). The urine analysis suggested
the involvement of kidney micro-vasculature. In addition, two nodular lesions with the cystic
pattern were observed in the CT scan of the lungs. However, the skin and nasal biopsies revealed
no evidence of chronic necrotizing vasculitis or granulomatous lesion. Nonetheless, treatment
was initiated with a strong suspicion of GPA. Following the treatment, the patient's symptoms
completely disappeared, and the diagnosis of GPA was confirmed.