**Core Concept**
Von-Hippel Lindau (VHL) syndrome is a rare, autosomal dominant disorder characterized by the development of multiple benign and malignant tumors. The syndrome is caused by mutations in the VHL gene, which plays a crucial role in regulating cellular growth and angiogenesis. VHL syndrome is associated with various types of tumors, including hemangioblastomas, renal cell carcinomas, and pancreatic neuroendocrine tumors.

**Why the Correct Answer is Right**
Hemangioblastomas are a hallmark of VHL syndrome, and they can occur in the craniospinal region, including the brain, spinal cord, and retina. These tumors are typically benign but can cause significant morbidity due to their location and potential for bleeding or compression of adjacent structures. The development of hemangioblastomas in VHL syndrome is thought to be related to the loss of VHL protein function, which leads to increased vascular endothelial growth factor (VEGF) expression and subsequent angiogenesis. Craniospinal hemangioblastomas are a common feature of VHL syndrome, occurring in approximately 70% of affected individuals.

**Why Each Wrong Option is Incorrect**
**Option A:** Multiple tumors are rarely seen. This statement is incorrect because VHL syndrome is characterized by the development of multiple tumors, including hemangioblastomas, renal cell carcinomas, and pancreatic neuroendocrine tumors.

**Option C:** Supratentorial lesions are common. This statement is incorrect because while supratentorial lesions can occur in VHL syndrome, they are less common than infratentorial lesions, which are more frequently associated with hemangioblastomas.

**Option D:** Tumors of Schwann cells are common. This statement is incorrect because tumors of Schwann cells, such as schwannomas, are not a common feature of VHL syndrome. Hemangioblastomas are the most characteristic tumors associated with this disorder.

**Clinical Pearl / High-Yield Fact**
A key feature of VHL syndrome is the development of hemangioblastomas, which can occur in the craniospinal region and are often associated with visual disturbances, neurological deficits, and other symptoms. Regular screening for these tumors is essential in affected individuals.

**✓ Correct Answer: B. craniospinal hemangioblastomas are common**