Sonographic target sign in neurofibromas

Neurofibromas are the most common tumors of the peripheral nerves. They may be solitary lesions, multiple localized lesions, or large plexiform masses often associated with neurofibromatosis. Relatively few reports discuss th e sonographic features of PNST, specifically neurofibromas.(1-7) The typica l sonographic description is that of a well defined, homogeneous hypoechoic lesion, which can show posterior acoustic enhancement mimicking a cystic l esion.(1,3,4) We present a case of neurofibromatosis in a 19 year old man, which was initially diagnosed by ultrasonography. We describe the ultrasono graphic findings that we believe correspond to the so-called target sign on T2-weighted MR imaging examinations. The appearance on T2-weighted MR imag es is reported as increased signal intensity peripherally and decreased sig nal intensity centrally.(8-10) A target sign appearance was seen sonographi cally in numerous lesions, demonstrating a hyperechoic central region and a hypoechoic periphery.