Can Lipomatosis of the Nerve Occur or Extend Intradurally?

Background: Diverse adipose lesions can affect peripheral nerves, including an intrinsic disorder known as lipomatosis of nerve (LN). This condition leads to massive nerve enlargement and has often been associated with nerve territory overgrowth. Although LN has been well documented as a peripheral lesion, it is uncertain whether LN can occur or extend intradurally. Methods: In the present 2-part study, we searched our institutional database and the world literature to identify any case of LN occurring or extending intradurally. Strict pathognomonic imaging and histopathologic features of LN were required to be present. Results: We did not identify any case of LN that had occurred or extended intradurally in our institution. Specifically, in our database, we found no case of intradural LN, and an evaluation of the imaging studies of proximal examples of LN did not show any extension proximal to the spinal foramen. Our literature search identified 208 reports of potential interest, of which only 3 had reported on spinal LN. Although 2 of the 3 cases showed some similarities to LN, none had demonstrated features diagnostic for LN and none had demonstrated nerve territory overgrowth. A review of 16 cases of LN in proximal locations summarized in a recently reported systematic review did not reveal any cases with LN proximal to the foramen or in an intradural location. Conclusion: A review of our institutional cases and reported cases did not show any example of LN extending or occurring intradurally. It appears that LN is a benign tumor-like nerve lesion that is without a central location, unlike more well-known tumors such as schwannomas.