[A case of lumbosacral lipoma and its interesting histological findings]

A case of 3-month-old girl with lumbosacral lipoma is reported. She had a large soft tissue mass (4 X 5 cm) in the lumbosacral region initially noted at birth. Interpendicular distances below L2 were dilated on X-P. CT image demonstrated a sharply outlined low density area (approximately -80 H. U.) which occupied the latter half of the spinal canal in the level of L2 to S1 level. Defect of vertebral arch was also seen. Lipoma was removed subtotally with laminectomy. CT image demonstrated clear sharp margin of the tumor, neural tissue free zone were not found intraoperatively. Post-operative course was uneventful. Specimen showed the mature adipose tissue which contained rich blood vessels and connective tissue. Connective tissue was composed of collagen fibers and elastic fibers. Small aberrant nerve fibers and smooth muscle fibers were sporadically noted in specimens obtained from nearby transitional area of its lipoma and spinal cord. Although there were a few reports about the morphology of lipoma, the existence of nerve cell, neuroglia, embryonic bone, cartilage, smooth muscle fiber, striated muscle fiber, respiratory-like cell and others were reported in the previous reports. Our histological findings also suggest that the lipoma possibly arise from pluripotential caudal cell mass which survived by disturbance of the 3rd stage of neural tube formation (retrogressive differentiation).