What are some clinical, CT and MRI features of neurofibroma?
Neurofibromas account for 5% of benign soft tissue neoplasms, are benign peripheral nerve sheath tumors, and most commonly occur in the third to fifth decades of life. The majority arise sporadically and are asymptomatic. However, 33% with a single neurofibroma have NF-1, and 99% with multiple or plexiform neurofibromas have NF-1. Surgical excision is usually performed when they are large in size, symptomatic, or suspicious for having undergone malignant transformation.
Solitary or multiple fusiform enhancing masses are usually seen in a retroperitoneal or paravertebral location, centered on parent nerves when visualized, often with a “bag of worms” configuration due to multiple diffusely thickened nerve branches as part of a plexiform neurofibroma. A dumbbell configuration may be seen when there is neural foraminal expansion by an involved spinal nerve. They usually have low soft tissue attenuation, low signal intensity on T1-weighted images, and high signal intensity on T2-weighted images relative to skeletal muscle, and they may be homogeneous or heterogeneous, sometimes with a “target” sign or else with a “whorled appearance” due to curvilinear low signal intensity foci on T2-weighted images