Expect the unexpected: a case of spontaneous thrombosis of a pial arteriovenous fistula in a preterm newborn with review of the literature.

INTRODUCTION: Pial arteriovenous fistulas (pAVF) are rare vascular malformations, especially in children and newborns. In neonates, the most common symptom is congestive heart failure. CASE PRESENTATION: We report a case of an asymptomatic preterm newborn incidentally diagnosed with pAVF during a routine cranial ultrasound (cUS) on the third day of life. Cerebral magnetic resonance (MRI) confirmed the diagnosis. A wait-and-see approach was chosen by the multidisciplinary team. The cUS and the MRI on day 14 of life showed the spontaneous resolution of the lesion. CONCLUSIONS: This case underlines the challenges in identifying pAVF in the first weeks of life and demonstrates a possible positive outcome for affected neonates.