system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 63-year-old man comes to the physician because of a 2-day history of fever and blood-tinged sputum. He has also had a productive cough for 1 year and has had 3 episodes of sinusitis during this time. Physical examination shows palpable erythematous skin lesions over his hands and feet that do not blanch on pressure. There are ulcerations of the nasopharyngeal mucosa and a perforation of the nasal septum. His serum creatinine is 2.6 mg/dL. Urinalysis shows acanthocytes, 70 RBCs/hpf, 2+ proteinuria, and RBC casts. An x-ray of the chest shows multiple, cavitating, nodular lesions bilaterally. Further evaluation of this patient is most likely to show which of the following findings?
assistant
Elevated c-ANCA titers