PTEN is a tumor suppressor and its inactivation has a role in plexiform neurofibroma tumorigenesis and progression to high-grade peripheral nerve sheath tumors in the context of NF1 loss in Schwann cells, which is a very variable symptom in NF1, and may also participate in the mechanism of tumorigenesis of other tumors related to NF1 [58,59]. The gene discussed is NF1; the disease is neoplasm.