A 20-year-old man presents with a palpable flank mass and hematuria. An ultrasound shows bilateral enlarged kidneys with cysts. What associated brain anomaly is commonly seen?

The presentation of a 20-year-old man with a flank mass, hematuria, and ultrasound findings of bilateral enlarged kidneys with cysts is suggestive of autosomal dominant polycystic kidney disease (ADPKD). An important aspect of this condition is its association with extrarenal manifestations, particularly central nervous system anomalies.

One of the most common brain anomalies associated with ADPKD are cerebral berry aneurysms. These aneurysms typically form at the bifurcations of the arteries in the circle of Willis and can lead to subarachnoid hemorrhage if they rupture. The mechanism behind this connection is believed to involve genetic and hemodynamic factors that affect vascular integrity, leading to increased susceptibility to aneurysm formation in individuals with ADPKD.

While conditions like medulloblastoma and hemangioblastoma are associated with other genetic syndromes (e.g., von Hippel-Lindau syndrome) or different clinical contexts, they are not specifically linked to ADPKD. Similarly, arteriovenous malformations are not a common association with this condition. Thus, recognizing the link between ADPKD and cerebral berry aneurysms is crucial for understanding the potential complications and management of patients with this genetic disorder.