PTEN and PTEN hamartoma tumor syndrome: Two rare brain tumors, meningiomas (8.25%) and gangliocytomas (1.8–15%), also have high incidence rates among PHTS patients; adult-onset dysplastic cerebellar gangliocytomas, or Lhermitte-Duclos disease, is specifically enriched for PTEN mutations (83%) [7,86,87].