067. PULMONARY INVOLVEMENT IN GIANT CELL ARTERITIS MIMIC

Abstract

Background: Giant cell arteritis (GCA) is the most common form of vasculitis that affects people aged over 50 years. GCA is a medical emergency that often progresses rapidly and, if left untreated. Case Description: An 82-year-old gentleman was admitted to our hospital with new onset headache, jaw claudication and c-reactive protein (CRP) 300mg/dL. Past history included repaired aortic aneurysm (2008) and obstructive lung disease. Diagnostic work-up including temporal artery biopsy (TAB) was negative. However, he was diagnosed with GCA and started on 60 mg prednisone. He was referred for a GCA ultrasound (US) assessment which revealed bilateral positive halo sign with involvement of the frontal, parietal, facial and occipital S branches. Treatment resulted in moderate improvement in his headache. One week after prednisone was reduced to 50mg, he suffered a severe relapse with headache and jaw claudication. He was admitted to hospital where immunological serology was negative with a CRP 100mg/dL and CT chest showed pulmonary infiltrates. There was hesitation from the pulmonary service to investigate further with bronchoscopy, as they felt the pulmonary manifestations were due to GCA. Three days of treatment with 1g methylprednisolone led to rapid symptom resolution and CRP reduction to 30mg/dL. Prednisone was continued at 50mg/d but attempts to taper to 45mg resulted in flares with severe headaches and bilateral temporal artery halo sign progression on serial US assessment. Investigation with PET scan showed multiple lung infiltrations and bilateral temporal artery uptake. The patient later disclosed that his brother was treated for tuberculosis (TB) 30 years ago which raised concern for TB. Diagnostic work-up with bronchoscopy surprisingly revealed pneumocystis jiroveci. Currently, the patient is on treatment with 28mg of methylprednisolone and trimethoprim and sulfamethoxazole with consideration for immunosuppression given the inability to taper prednisone. Discussion: Pulmonary manifestations of GCA are nonspecific and rare. Upper tract symptoms include sore throat and cough. Lower tract involvement includes pulmonary nodules, interstitial infiltrates, alveolitis and subclinical hemorrhage. Occam would have us consider that this patient had a rare manifestation of uncommon disease. Whereas, Hickam would correctly advise us that a second more common disease process such as infection induced by treatment is likely. Conclusion: It is vital to rule out common causes of pulmonary manifestations when treating vasculitis patients.