PC2145: Incidental Hypoxemia: A Case of Pulmonary Arteriovenous Malformations and Brain Abscess

Introduction: Approximately 40% of pulmonary AVMs are asymptomatic and/or incidentally identified on chest radiography as nodular opacities. The rare incidence of isolate pulmonary AVMs often results in misdiagnosis and neurological complications at the time of presentation.

Case Description: A 38-year-old previously healthy female presented to the ambulatory clinic with intermittent left upper chest wall pain. Vital signs were significant for oxygen saturation of 89%. During her visit, continuous pulse oximetry demonstrated oxygen saturations between 88-91%. Saturations improved with walking to 92-96%. At a recent urgent care visit for similar complaints, a CBC was obtained and was concerning for mild polycythemia with a hemoglobin of 15.8 g/dL. Chest x-ray demonstrated nodular opacity over the left midlung. At her clinic visit, repeat CBC, non-contrast CT chest, and trans-thoracic echocardiogram were ordered. The patient was lost to follow up until she presented to the emergency department (ED) with nausea, vomiting, headaches, and fevers 1 month later. CT chest was obtained and revealed an AVM in the superior left lower lobe corresponding to the opacity in the radiograph, the pulmonary artery supplying the AVM measured 6 mm in diameter. It further revealed a smaller lingular pulmonary AVM, with a 4 mm pulmonary artery supplying this AVM, and a small AVM was seen along the pleural surface of the inferior lingula. Given the association of pulmonary AVMs with intracerebral abscesses, an MRI brain was obtained. MRI demonstrated a right temporal lobe abscess with surrounding vasogenic edema and 5 mm right to left midline shift. She was emergently taken to the operating room for right bur hole craniotomy for stereotactic aspiration of intracerebral abscess. Abscess fluid cultures grew Streptococcus Intermedius, and intravenous ceftriaxone and metronidazole were initiated. The patient revealed she had recently had a dental cleaning. Interventional radiology was consulted and subsequently performed coil embolization of 4 pulmonary artery branches feeding 3 separate pulmonary AVMs. She was discharged home on IV ceftriaxone and metronidazole with neurosurgery and infectious disease follow up. Follow up MRI brain 6 weeks after initial presentation demonstrated continued decrease in size of the right temporal abscess with improvement in surrounding vasogenic edema. She has completed IV antibiotic therapy and continues to demonstrate significant symptomatic improvement.

Discussion: Pulmonary AVMs are commonly associated with hereditary hemorrhagic telangiectasias, however idiopathic isolated pulmonary AVMs are rare vascular anomalies. They are usually identified in the fourth to sixth decade of life with neurological complications such as stroke, brain abscess, TIA, migraines, and seizures. Paradoxical embolization across AVMs are the likely mechanism of brain abscesses and stroke, more commonly seen with feeding arteries >2-3mm in diameter.

Conclusion: Given the considerable risk of devastating neurological complications, pulmonary AVMs should be on the differential for patients with unexplained hypoxemia, dyspnea, chest pain, or hemoptysis.