Accessory Posterior Cerebral Artery-The Hyperplastic Anterior Choroidal Artery Variant.

Variants of the cerebral arterial circle, both common and rare, are frequently documented. The authors present a distinct case involving a 54-year-old male patient who underwent a computed tomography angiogram (CTA), which was analyzed using planar slices and 3-dimensional reconstruction. In this case, the left posterior cerebral artery (PCA) received the posterior communicating artery (PComA) 7 mm distal to its origin from the basilar artery (BA). In addition, an accessory vessel originated 4.2 mm distal from the PComA origin, branching from the left internal carotid artery (ICA). This vessel was identified as an accessory posterior cerebral artery (APCA), corresponding to a hyperplastic anterior choroidal artery (AChA). This case illustrates a rare variant in the posterior circulation of the brain, in which the territory of the PCA is supplied by both the internal carotid and vertebrobasilar systems.