Ruptured infected lumbar spinal canal dermoid cyst with intramedullary abscess and holocord edema
Urinary bladder dysfunction. Skin dimple on lower back
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T2w hypointense and T1w isointense linear band is noted in the posterior lower lumbar subcutaneous fat extending obliquely from the puckered skin surface (externally) upto the spinal canal at the level of 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 upper border of L2 to lower border of L5 vertebral levels showing 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 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 oedema. 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.
2 case question available
A 6-month-old child presented with bladder dysfunction to the paediatric neurologist. Clinically, there was a small dimple in the posterior lower lumbar soft tissue. The child was referred for MRI whole spine screening to rule out any occult spinal dysraphism, spinal canal mass and cord pathology.
MRI whole spine showed T2w hypointense band in the lower lumbar posterior subcutaneous region extending from skin obliquely into the spinal canal at lumbosacral junction, consistent with dorsal dermal sinus tract.
T2w hypointense intradural spinal canal mass lesion was noted in lumbar spine extending from L2 to L5 levels with thick peripheral enhancement, representing an infected dermoid cyst. Dermal sinus tract was leading up to the lesion. There was rupture of the infected dermoid cyst into 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. Rupture of 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 few of the cases.
- 1. Sudhakar Vadivelu, Sohum K Desai, Anna Illner, Thomas G Luerssen, Andrew Jea. Infected lumbar dermoid cyst mimicking intramedullary spinal cord tumor: Observations and outcomes. (2014) Journal of Pediatric Neurosciences. 9 (1): 21. doi:10.4103/1817-1745.131475 - Pubmed
- 2. Takao Tsurubuchi, Akira Matsumura, Kei Nakai, Keishi Fujita, Takao Enomoto, Nobuaki Iwasaki, Tadao Nose. Reversible Holocord Edema Associated with Intramedullary Spinal Abscess Secondary to an Infected Dermoid Cyst. (2018) Pediatric Neurosurgery. 37 (6): 282. doi:10.1159/000066306 - Pubmed