- Diagnosis Patients with NF1 and progressive, symptomatic or life-threatening plexiform neurofibromas which are not surgically resectable. Patients without biopsy-proof of plexiform must have at least one other diagnostic criteria for NF1: 6 or more cafe-au-lait spots, freckling in the axilla or groin, optic glioma, 2 or more Lisch nodules, distinctive bony lesion, first degree relative with NF1.