What is the most common brain tumor associated with neurofibromatosis type 1 (NF1), and what are its key imaging characteristics?

Pilocytic astrocytoma is the most common brain tumor associated with NF1, typically presenting as a cystic lesion with an enhancing mural nodule on MRI. These tumors often occur in the cerebellum and optic pathways. Key diagnostic features include a well-circumscribed mass with low-grade histology. A common pitfall is confusing it with other cystic lesions such as ganglioglioma or low-grade gliomas, but the presence of NF1 and characteristic imaging can guide diagnosis.