Misdiagnosis of plexiform neurofibroma as venous malformation in pediatric patients.

Background: The aim of this study was to identify Magnetic Resonance Imaging (MRI) characteristics that reliably distinguish deep plexiform neurofibromas (PNFs) from venous malformations (VMs).

Methods: A database search was conducted for patients that were referred with a vascular anomaly but had a neurofibroma instead. Clinical and imaging features of patients with venous malformations as the most common referral diagnosis were compared to those with PNFs. The imaging features of deep PNFs recorded were: anatomical location, size, morphology, margins, signal intensity and post-contrast enhancement pattern.

Results: Ten patients with PNFs were identified. Five patients had adequate imaging. These five patients were included in our study. There were 3 female and 2 male patients ranging in age from 10 months to 21 years. Deep PNFs were located in the cervicofacial region (N.=3), lower extremity (N.=1) and back/flank region (N.=1). The most common clinical features of all these patients were palpable mass (N.=5) and pain (N.=4). The MRI features that distinguished VMs from deep PNFs were the serpiginous morphology, relatively intermediate T-2 signal intensity and peculiar enhancement pattern without fluid-fluid levels or phleboliths and nerve root involvement. The target sign can be regularly found in PNFs, but may be also present in VMs and other vascular lesions.

Conclusions: Target signs, a typical sign of PNFs may be absent and can also be found in vascular anomalies, leading to confusion in diagnosis. PNFs can be reliably distinguished from VMs on MRI based on the above mentioned features.