Brain abscess as the first clinical manifestation of isolated pulmonary arteriovenous malformation without Rendu-Osler disease
Brain abscesses occur in 5 to 13 % of patients with pulmonary arteriovenous malformation (PAVM), more often present in Rendu-Osler-Weber disease or hereditary hemorrhagic telangiectasia (HHT). A 51-year-old man with a history of transient Parinaud syndrome at 37 years complained of **headache** for 2 months before **acute onset of a left cerebellar syndrome without fever.** CT-scan and **MRI of the head revealed a heterogeneous left cerebellar lesion.** **A brain abscess was drained and all signs resolved.** CT-scan of the chest revealed a left lingual PAVM; occlusion was incomplete after **coil embolization.** He had no feature of HHT and no mutation in ENG and ACVRL1 genes. A **second embolization** was performed 5 months later, but the malformation was not occluded at 6 months. We report the seventh case of PAVM complicated by a cerebellar abscess. The right to left shunt in PAVM results in hypoxemia, secondary polycythemia and paradoxical embolization of infective organisms bypassing the pulmonary filter. Combining different MRI techniques (in particular diffusion and proton MR spectroscopy) provides invaluable data for the diagnosis of brain abscess. Careful search for PAVM must be undertaken, particularly in adults with cryptogenic abscess, to avoid further abscess formation or stroke.