Selumetinib in the Treatment of Orbital Plexiform Neurofibroma: A Case Report.

A 4-year-old boy with a known diagnosis of neurofibromatosis 1 (NF1) and a diffusely infiltrative plexiform neurofibroma (PN) of the left orbit was started on selumetinib treatment for progressively worsening amblyopia. The patient first presented with new-onset left ptosis at 11 months old. He subsequently developed refractory anisometropic amblyopia of the left eye, in addition to clinically significant left proptosis and hypoglobus that interfered with glasses wear for his amblyopia treatment. The plexiform neurofibroma was not amenable to surgical resection and selumetinib treatment was initiated 3 years after the initial diagnosis. The patient showed remarkable clinical and radiographic improvement in tumor burden after treatment. Best corrected visual acuity improved from 20/50 to 20/20- in his amblyopic eye. Relative proptosis of the affected eye also improved from 4mm to 2mm on Hertel measurements, which allowed for consistent glasses wear. Adverse effects from the treatment were limited to an acneiform rash, which resolved following dose reduction according to the FDA dosing guidelines.