Dermal Sinus Tract¶

Definition¶

A dermal sinus tract is a congenital epithelium-lined tract extending from the skin surface inward toward (and sometimes into) the spinal canal, potentially extending to the thecal sac / neural placode. It represents a failure of complete separation of cutaneous ectoderm from neural ectoderm during embryological development. The tract may terminate in the subcutaneous tissues, the epidural space, or extend to the dura, subarachnoid space, or even the spinal cord. It is most common in the lumbosacral region.

Clinical Significance¶

The dermal sinus tract provides a direct conduit for bacteria from the skin surface to the intrathecal space, creating a risk of recurrent meningitis, epidural abscess, and intraspinal dermoid or epidermoid cysts (from desquamated epithelial cells).

Imaging Findings¶

MRI¶

A thin tract extending from the skin surface through the subcutaneous fat and posterior elements toward the thecal sac
The tract may terminate in the epidural space, subdural space, or at the cord surface
Dermoid or epidermoid cyst — May form at the intradural end of the tract (T1-bright for dermoid due to fat content; variable for epidermoid)
Low-lying conus and tethered cord may be associated
Post-contrast images may show enhancement along an infected tract

CT¶

Posterior bony defect at the level of the tract
The soft tissue tract is difficult to see on CT

Clinical Pearl

A midline skin dimple or pit above the gluteal cleft with surrounding hair or skin changes should raise concern for a dermal sinus tract — unlike a simple sacral dimple (within the cleft), which is benign. A child with recurrent meningitis of unknown source should be evaluated for a dermal sinus tract with MRI of the spine.

Key Points¶

Epithelium-lined tract from skin to spinal canal — risk of infection and dermoid/epidermoid formation
Most common in the lumbosacral region
MRI is the modality of choice — trace the tract from skin to its termination
Recurrent meningitis in a child should prompt evaluation for a dermal sinus
Surgical excision of the tract is indicated to prevent recurrent infection

References¶

Gaillard F, et al. Dorsal dermal sinus. Radiopaedia.org. Available at: https://radiopaedia.org/articles/dorsal-dermal-sinus
Lee SM, Cheon JE, Choi YH, Kim IO, Kim WS, Cho HH, Lee JY, Wang KC. Limited Dorsal Myeloschisis and Congenital Dermal Sinus: Comparison of Clinical and MR Imaging Features. AJNR Am J Neuroradiol. 2017;38(1):176–182. PMID: 27765739. PMCID: PMC7963655.
Barkovich AJ, Edwards MS, Cogen PH. MR evaluation of spinal dermal sinus tracts in children. AJNR Am J Neuroradiol. 1991;12(1):123–129. PMID: 1903240.
Lane J, Dias M, Iantosca M, Zacharia T, Tubbs RS, Rizk E. Dermal Sinus Tract of Lumbosacral Spine in Children: Patterns on Magnetic Resonance Imaging and Scoring System. Cureus. 2017;9(12):e1906. doi:10.7759/cureus.1906. PMID: 30944782. PMCID: PMC6438690.
Singh I, Rohilla S, Kumar P, Sharma S. Spinal dorsal dermal sinus tract: An experience of 21 cases. Surg Neurol Int. 2015;6(Suppl 17):S429–S434. PMID: 26539316. PMCID: PMC4604646.