Imaging of musculoskeletal neurogenic tumors: Radiologic-pathologic correlation

Numerous neurogenic tumors can affect the musculoskeletal system, including traumatic neuroma, Morton neuroma, neural fibrolipoma, nerve sheath gangli on, neurilemoma, neurofibroma, and malignant peripheral nerve sheath tumors (PNSTs), The diagnosis of neurogenic tumors can be suggested from their im aging appearances, including lesion shape and intrinsic imaging characteris tics. It is also important to establish lesion location along a typical ner ve distribution (eg:, plantar digital nerve in Morton neuroma, median nerve in neural fibrolipoma, large nerve trunk in benign and malignant PNSTs), T raumatic and Morton neuromas are commonly related to an amputation stump or are located in the intermetatarsal space, respectively. Neural fibrolipoma s show fat interspersed between nerve fascicles and are often associated wi th macrodactyly. Nerve sheath ganglion has a cystic appearance and commonly occurs about the knee. Radiologic characteristics of neurilemoma, neurofib roma, and malignant PNST at computed tomography (CT), ultrasonography, and magnetic imaging include fusiform shape, identification of entering and exi ting nerve, low attenuation at CT, target sign, fascicular sign, split-fat sign, and associated muscle atrophy. Although differentiation of neurilemom a from neurofibroma of beni:pn from malignant PNST is problematic, recognit ion of the radiologic appearances of neurogenic tumors often allows prospec tive diagnosis and improves clinical management of patients.