Rare focal neural lesion
Slowly progressive painless mononeuropathy
Onion bulb–shaped whorls of neoplastic perineural cell proliferation
On ultrasound it appears hypoechoic with mildly elongated fusiform enlargement of the involved nerve
Reference:
Stuart RM et al. Sonography of Peripheral Nerve Pathology . AJR 2004; 182:123-129
