We provide a suggested framework for adequate interventional radiology and surgical sampling and recommend molecular profiling for clinically or radiologically worrisome noncutaneous lesions in patients with NF1 to identify diagnostically relevant molecular features, including CDKN2A/B inactivation for ANNUBP, as well as SUZ12, EED, or TP53 inactivating mutations, or significant aneuploidy for MPNST. The gene discussed is CDKN2A; the disease is malignant peripheral nerve sheath tumor.