**Core Concept**
Venous malformations involving the leptomeninges of the cerebral cortex refer to abnormal vascular structures within the meninges that surround the brain. These malformations can be associated with various neurological conditions, including Sturge-Weber syndrome.

**Why the Correct Answer is Right**
Sturge-Weber syndrome is a rare neurocutaneous disorder characterized by the presence of a port-wine stain on the face, typically involving the ophthalmic division of the trigeminal nerve. The syndrome is also associated with leptomeningeal angiomatosis, which involves a network of abnormal blood vessels within the leptomeninges. These malformations can lead to seizures, developmental delays, and other neurological symptoms. The leptomeningeal angiomatosis is thought to result from the abnormal development of the blood vessels during embryogenesis.

**Why Each Wrong Option is Incorrect**
* **Option A:** Sturge-Weber syndrome is not primarily characterized by leptomeningeal angiomatosis in the setting of Klippel-Trenaunay-Weber syndrome, a different condition that involves the development of vascular malformations in the skin and soft tissues.
* **Option B:** Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) is a genetic disorder that involves the formation of vascular malformations, but it is not primarily associated with leptomeningeal involvement.
* **Option C:** Cerebral cavernous malformations are a distinct type of vascular malformation that typically involve the brain parenchyma rather than the leptomeninges.

**Clinical Pearl / High-Yield Fact**
Sturge-Weber syndrome is often associated with a characteristic "tram-track" calcification pattern on CT or MRI scans, which can be a useful diagnostic clue in patients with suspected leptomeningeal angiomatosis.

**Correct Answer:** D.