Pearls & Oy-sters: Cerebral Abscess Secondary to Pulmonary Arteriovenous Malformation in Hereditary Hemorrhagic Telangiectasia.

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant condition that is linked to a myriad of neurologic complications arising from vascular malformations of the brain, spinal cord, and lungs. Our case describes a previously healthy 3-year-old male who presented to hospital with fever of unknown origin and was found to have a brain abscess stemming from a pulmonary arteriovenous malformation (PAVM). This etiology was identified after a period of diagnostic delay; the medical team was suspicious for a proximal embolic source due to the presence of multiple tiny infarcts seen on MRI of the brain, but transthoracic echocardiogram and head and neck angiogram were unremarkable. Fortunately, an enhanced CT of the chest was performed, identifying a moderately sized PAVM. PAVMs are associated with intracranial abscesses due to shunting and loss of the normal filtering effects of the lung capillary bed. Impaired pulmonary filtration can permit paradoxical thromboemboli and septic microemboli to enter systemic circulation, predisposing patients with PAVMs to cerebral abscess and ischemic stroke. Screening for PAVMs with contrast-enhanced echocardiogram or enhanced CT of the chest may be considered in patients with cryptogenic brain abscess or recurrent embolic stroke of unknown origin. PAVMs are often associated with hereditary hemorrhagic telangiectasia (HHT). As many features of HHT have delayed clinical manifestation, genetic testing for HHT should be considered in all people with PAVM, even in the absence of other clinical features. In our case, genetic testing returned positive, confirming a new diagnosis of HHT type 1.