Abstract
Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder caused by mutations in the NF1 gene, including exon deletions, which are associated with various phenotypes and plexiform neurofibromas. Plexiform neurofibromas are clinically observed in up to 30% (and up to 50% on MRI) of NF1 patients and may involve both external and internal tissues, with a risk of malignant transformation to malignant peripheral nerve sheath tumors (MPNST). This report presents a rare case of a large plexiform neurofibroma in an adolescent male with NF1, involving the hepatic hilum and surrounding hepatic vessels. The patient, born in 2002, presented with multiple café-au-lait macules, cutaneous neurofibromas, axillary freckling, and headaches. Imaging studies, including 3-Tesla MRI and multislice CT, revealed a multinodular lesion extending along the hepatic vessels, around the gallbladder, the celiac trunk, and adjacent pancreatic and duodenal structures. Genetic testing confirmed a large deletion of an exon in the NF1 gene. Due to the lesion’s inoperable location and risk of vascular and biliary compression, targeted therapy with the MEK inhibitor selumetinib was indicated. The patient is currently awaiting provision of the medication. This case underscores the importance of careful monitoring and early initiation of targeted therapy in NF1 patients with extensive plexiform neurofibromas, particularly those caused by large NF1 gene deletions, which result in complete loss of neurofibromin and extensive infiltrative benign tumor growth.