Nonoperative Management May Be a Viable Approach to Plexiform Neurofibroma of the Porta Hepatis in Patients with Neurofibromatosis-1

Neurofibromatosis Type 1 with a Giant Diffuse Plexiform Neurofibroma Invading the Liver

Plexiform neurofibromas (PNs) occur in approximately 50% of patients with neurofibromatosis type 1 (NF1). PNs are rare in the abdominal cavity and especially rare in hepatobiliary lesions. A 31-year-old man with NF1 had a tumor extending along the celiac artery, superior mesenteric artery, and intrahepatic portal vein. We diagnosed him with diffuse PN based on liver tumor biopsy findings and the tumor form. Because the tumor had invaded along the intrahepatic portal vein, surgical resection was deemed difficult, and the patient was followed up with imaging studies. The patient remained asymptomatic without tumor growth.

Abdominal neoplastic manifestations of neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary tumor syndrome, with a wide clinicopathologic spectrum. It is defined by characteristic central nervous system, cutaneous and osseous manifestations, and by mutations in the NF1 gene, which is involved in proliferation via p21, RAS, and MAP kinase pathways. Up to 25% of NF1 patients develop intra-abdominal neoplastic manifestations including neurogenic (commonly plexiform neurofibromas and malignant peripheral nerve sheath tumors), interstitial cells of Cajal (hyperplasia, gastrointestinal stromal tumors), neuroendocrine, and embryonal tumors (rhabdomyosarcoma). Nonspecific symptoms, multifocal disease, or coexistence of 2 or more tumor types make patients challenging to diagnose and manage. Screening for intra-abdominal tumors in NF1 patients remains controversial, and currently no guidelines are established. Management decisions are complex and often informed by single-center experiences or case studies in the literature, though the field is rapidly evolving. Thus, NF1 patients should be followed in specialist centers familiar with their wide spectrum of pathology and with multidisciplinary care including specialized pathology and radiology. This review will (1) provide a contemporaneous synthesis of the literature and our multi-institutional clinical experiences with intra-abdominal neoplasms in NF1 patients, (2) present a classification framework for this heterogeneous group of disorders, and (3) outline approaches to screening, surveillance, diagnosis, and management.