Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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November 17, 2022
Lipomyelocele with ossified dysraphic hamartoma
•Background:
- Lipomyeloceles are a type of closed spinal dysraphism that result from a defect in primary neurulation whereby mesenchymal tissue enters the neural tube and forms lipomatous tissue. Rarely, these may be associated with aberrant tissues such as cartilage, striated muscle, neural cells, and bone, with presence of completely formed bone known as ossified dysraphic hamartoma being extremely rare.
•Clinical Presentation:
- Present with a nontender subcutaneous mass, usually located in median or paramedian location in the thoracolumbar region, often present since birth.
•Key Diagnostic Features:
- MRI is the modality of choice to diagnose and characterize the lesion, often showing a posterior spinal defect that is covered with skin associated with interspersed lipomatous tissue (T1 and T2 hyperintense). The neural placode-lipoma interface lies within the spinal canal or at its edge with normal anterior subarachnoid space.
- May be associated with tethered low-lying cord or syrinx of the terminal spinal cord.
- CT is useful in evaluating the bony component of the lesion; articulation with surrounding bones that helps in surgical planning.
•Differential Diagnosis:
- Lipomyelomeningocele: The lipoma-placode interface lies outside the spinal canal with resultant enlargement of anterior subarachnoid space.
- Intradural spinal lipoma: Sharply circumscribed masses intradural in location and distorting the cord. These follow fat signal on all sequences.
- Lipoma of the filum terminale: Typically, linear fat intensity involving the filum extending for some length, may be associated with tethered-cord syndrome.
•Treatment:
- Surgical resection, and may often require additional planning in cases of articulating or nonarticulating dysraphic bone.
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