Ruptured infected lumbar spinal canal dermoid cyst with intramedullary abscess and holocord edema
Presentation
Urinary bladder dysfunction. Skin dimple on lower back
Patient Data
A T2w hypointense and T1w isointense linear band is noted in the posterior lower lumbar subcutaneous fat, extending obliquely from the puckered skin surface (externally) up to the spinal canal at the level of the lumbosacral junction, representing a dorsal dermal sinus tract.
A well-defined T2w hypointense and T1w isointense intradural mass lesion is noted in the lumbar spinal canal, extending from the upper border of L2 to the lower border of L5 vertebral levels. It shows thick peripheral enhancement with few internal septations, representing an infected dermoid cyst.
There is mild enhancement of the dorsal dermal sinus tract, representing inflammation. This dermal sinus tract is seen communicating with thecal sac contents at the level of the lumbosacral junction.
Conus medullaris could not be identified. The superior end of peripherally enhancing infected dermoid cyst shows focal discontinuities, representing rupture resulting in thick walled peripherally enhancing intramedullary abscess.
There are expansion and diffuse T2w hyperintensity of the spinal cord extending superiorly up to mid-C4 level, representing holocord edema. There is also extensive leptomeningeal enhancement along the entire spinal cord. Mild dural enhancement is also noted.
No evidence of hydrocephalus observed in the sagittal images.
Case Discussion
A 6-month-old child presented with bladder dysfunction to the pediatric neurologist. Clinically, there was a small dimple in the posterior lower lumbar soft tissue. The child was referred for an MRI whole spine screening to rule out any occult spinal dysraphism, spinal canal mass and cord pathology.
MRI of the whole spine showed a T2w hypointense band in the lower lumbar posterior subcutaneous region extending from the skin obliquely into the spinal canal at the lumbosacral junction, consistent with a dorsal dermal sinus tract.
T2w hypointense intradural spinal canal mass lesion was noted in the lumbar spine extending from L2 to L5 levels with thick peripheral enhancement, representing an infected dermoid cyst. The dermal sinus tract led up to the lesion. The infected dermoid cyst ruptured into the cord, resulting in an intramedullary abscess.
The child was advised admission and surgical management. However, the parents went against medical advice. Hence, lost to follow-up.
Up to 50% of the cases of dermal sinus tracts are associated with intraspinal dermoid cysts.
Intradural spinal canal dermoid cysts can undergo various complications, including rupture (leading to chemical meningitis) and infection. The rupture of a non-infected cyst results in chemical meningitis. An infected dermoid cyst has a heterogeneous MRI appearance, and its rupture into the spinal cord has been reported in a few cases.
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