Age / Sex : 0 / F

no clinical information (including age, sex, and chief complaint)

What is your impression?

Two weeks later, you can see the final diagonosis with a brief discussion of this case (Please submit only one answer).

Courtesy:  Dong-Ho, Ha, Dong-A university Hospital

Discussion

Answer: lipomyelocele

Findings:

MRI

1. Fat signal intensity mass within the spinal canal

Fatty mass is continuous with the adjacdent subcutaneous fat

2. Disruption of posterior spinal elements, but intact overlying skin


3. Lipoma placode interface with low signal intensity is within the spinal canal.

Differential Diagnosis:

Closed spinal dyraphism

Congenital spinal lipomatous malformations

1. Lipomyelocele


2. lipomyelomeningocele

Diagnosis: 

lipomyelocele

Discussion:

Congenital malformations of spine and spinal cord are collectively termed as spinal dysraphism. On the basis of presence or absence of overlying skin covering, spinal dysraphism is divided into open and closed types. In an open spinal dysraphism, there is a defect in the overlying skin, and the neural tissue is exposed to the environment. In a closed spinal dysraphism, the neural tissue is covered by skin.

Closed spinal dysraphism CSD can be further divided based on the presence or absence of associated subcutaneous mass.

Closed spinal dysraphisms

1. With subcutaneous mass


2. Lipomyelomeningocele


3. Lipomyelocele


4. Terminal myelocystocele


5. Meningocele


6. Myelocystocele


7. Without subcutaneous mass


8. Simple dysraphic states


9. Intradural lipoma


10. Filar lipoma


11. Tight filum terminale


12. Persistent terminal ventricle


13. Dermal sinus


14. Complex dysraphic states


15. Dorsal enteric fistula


16. Neuroenteric cyst


17. Diastematomyelia


18. Caudal agenesis


19. Segmental spinal dysgenesis

Lipomyeloceles and lipomyelomeningoceles is a spinal canal lipoma with deect and is a kind of closed spinal dysraphism with subcutaneous mass. These abnormalities result from defective primary neurulation where there is premature focal disjunction of cutaneous ectoderm and neuroectoderm allowing mesenchyme to enter the neural tube. This mesenchyme later forms the lipomatous tissue for unknown reasons.

The main differentiating feature between lipomyelocele and lipomyelomeningocele is the position of the placode–lipoma interface. With a lipomyelocele, the placode–lipoma interface lies within the spinal canal. With a lipomyelomeningocele, the placode–lipoma interface lies outside of the spinal canal due to expansion of the sub-arachnoid space. In both cases, syringomyelia is a commonly associated finding. Lipomyelocele and lipomyelomeningocele account for 20–56% of occult spinal dysraphism and 20% of skin-covered lumbosacral masses.

References:

Acta Neurochir (Wien). 2009 Mar;151(3):179-188

AJR 2010;194:S26–S37