Surveillance for Malignant Transformation of Neurofibromatosis Type 1 (NF1) Related Peripheral Nerve Sheath Tumors (PNST)

Shown exactly as written on ClinicalTrials.gov. Your oncologist is the right person to judge whether it fits your situation.

* INCLUSION CRITERIA:

High-Risk and Low-Risk NF1 Cohorts

* Age \>= 3 years old
* Participants with clinical or genetic diagnosis of NF1.
* Participants with a diagnosis of mosaic or segmental NF1 are also eligible.
* Individuals may have (High-Risk Cohort) or not have (Low-Risk Cohort) at least one of the following characteristics:

  * Microdeletion or 844-848 missense variants or other variants associated with increased risk of malignant peripheral nervous sheath tumor (MPNST)
  * Family history of MPNST / atypical neurofibromatous neoplasm of unknown biologic potential (ANNUBP) / atypical neurofibromas (ANF)
  * Personal history of MPNST/ANNUBP/ANF or neurofibroma with CDKN2A loss
  * Prior radiation therapy at any site
  * Large plexiform neurofibroma (PN) burden (\>= 350 mL)
  * Presence \>= 1 DNL at baseline
* The ability of the individual, parent/guardian or Legally Authorized Representative (LAR) to understand and the willingness to sign a written consent document for participation.

EXCLUSION CRITERIA:

High-Risk and Low-Risk NF1 Cohorts

\- Inability or unwillingness to undergo MRI imaging

INCLUSION CRITERIA:

Parent Cohort

* Parent or guardian of pediatric individuals (8-17 years old) in High-Risk or Low-Risk Cohorts.
* The ability of the parent/guardian or LAR to understand and the willingness to sign a written consent document for parent/guardian participation in this study.

EXCLUSION CRITERIA:

Parent Cohort

\- None.