Pathogenesis of lumbosacral lipoma: A test of the 'premature dysjunction' theory

Premature separation of the neuroectoderm from the ipsilateral surface ecto derm allowing mesenchymal tissue to invade into the central canal, or 'prem ature dysjunction' theory, was proposed for the pathogenesis of dorsal type lumbosacral lipoma. To test this theory, the unilateral neural fold was in cised using Hamburger and Hamilton stage 12 or 13 chick embryos. Among 35 e mbryos evaluated, 15 showed abnormal findings, and of these one showed find ings which suggested lumbosacral lipoma: a back lump, blending of the neuro epithelium and mesenchyme through indistinct basement membrane and vertebra l body abnormalities. The other 14 embryos showed abnormalities including b lunt tails, open neural tube defects, incomplete closure of the dorsal neur oepithelium with intact skin, skin dimples, disorganized gray matter, scoli osis, ectopic neuroepithelium and an accessory spinal cord. The results rev ealed that the incision of the unilateral neural fold in the early chick em bryo may produce a lesion suggestive of lumbosacral lipoma, a finding which supports the premature dysjunction theory. This method needs further refin ement to overcome technical difficulties, high mortality, and a low yield b efore being adopted as an experimental model for lumbosacral lipoma. Copyri ght (C) 2001 S. Karger AG, Basel.