The goal of this clinical research study is to learn if a handheld Mass Spectrometry device (MasSpec Pen) can accurately distinguish between masses, neurofibroma, and normal tissue during surgery.

Primary Objectives:

Aim 1. Determine the metabolite and lipid profiles of MPNST, neurofibroma, and nerve tissues

Aim 2. Validate the handheld mass spectrometry device (MSPen-Orbitrap system) for MPNST and neurofibroma diagnosis and for intraoperative surgical margin evaluation

Inclusion Criteria:

1. This study will enroll approximately 60 participants diagnosed with either MPNST or neurofibroma who are undergoing surgical resection of an MPNST or neurofibroma as part of their standard of care.
2. Age ≥ 1 years. Individuals younger than 18 years old will be included. For patients of age < 18 years, both parents' signatures will be requested.
3. Patients must have measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension as ≥10 mm (≥1 cm) with CT scan, MRI, or calipers by clinical exam.
4. Recurrent or primary disease.
5. Patients who are > 18 years should have the ability to understand and the willingness to sign a written informed consent document.
6. English and non-English speaking patients.

Exclusion Criteria:

1. Adult patients with cognitive impairment requiring a legally authorized representative for consent.
2. Patients under age 1 and neonates.
3. Patients who are pregnant and undergoing surgery for MPNST are not eligible.

For Aim 1: 100 neurofibromas and 104 MPNST snap-frozen, clinically and pathologically annotated samples have been identified. These have been collected under protocol LAB06-0851.

For Aim 2: We will evaluate the technology in the OR and enable surgeons to collect molecular data from a cohort of 60 patients undergoing resection of suspected or diagnosis of MPNST/neurofibroma (protocol: 2019-1118).