Age / Sex : 47 / F

Chief complaint : Buttock skin lesion with inflammation

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 of Jina Park, SMG-SNU Boramae Medical Center

Discussion

Answer:  Dorsal dermal sinus with diastematomyelia 

Findings:

Cord like structure in a paramedian location at lumbosacral area, connecting the skin and dural sac.

Associated split cord malformation with single dural sac (type I diastematomyelia) and low lying tethered spinal cord.

Differential Diagnosis:

Simple sacral dimple

Pilonidal sinus

Other causes of cord tethering

Discussion:

1. Diastematomyelia: split cord malformation (SCM)

• 1 in 5499 live births (0.02%), slight female predominance (1.3:1)


• Classification

Type I: duplicated dural sac, with common midline spur (osseous or fibrous), vertebral abnormalities, usualy symptomatic

Type II: single dural sac containing both hemicords, spina bifida may be present, but other vertebral anomalies are far less common, less symptomatic or may even be asymptomatic

2. Dorsal dermal sinus: epithelium-lined tract from the skin into the underlying structures with variable depth (may terminate within the thecal sac)

• 1 in 2500 live births (0.05%)


• frequently associated with other anomalies of the CNS such as tethered cord, inclusion tumors and split cord malformation


• manifests as a small dimple or pinpoint ostium, which is often associated with an area of hyperpigmented, angiomatous skin or hypertrichosis and occurs in a midline location or rarely in a paramedian location.


• ultrasonography can show the entire length of the tract , but dural penetration is difficult to ascertain or exclude on sonography

References:

Huang SL et al. Diastematomyelia: a 35-year experience. Spine. 2013;38(6):E344-E349.

Radmanesh F et al. Dermal sinus tract of the spine. Childs Nerv Syst. 2010;26:249-357.