Primary Diagnosis

Dermoid cyst of the filum terminale.

Secondary Diagnosis

N/A

Diagnosis Discussion

Dermoid cysts are rare developmental tumors associated with midline closure defects. They are common in the lower spine in the intradural extramedullary location. In the spinal canal, 60% occur in the lumbosacral region. Patients present with progressive lower extremity neurologic and bladder sphincter dysfunction because of cord tethering. The presence of a sinus tract, sacral dimple, tufts of hair, or spina bifida can be important clues leading to the diagnosis. An associated dermal sinus occurs approximately 20% of the time. A dermoid cyst typically has a heterogeneous appearance on MR images. T1-weighted images may show hyperintensity consistent with secretions of sebaceous glands, liquid lipid metabolites, and cholesterol from decomposed epithelial cells of the cyst wall. The solid cholesterol present in the dermoid cyst can cause prolonged T1 relaxation. Solid components of a dermoid cyst are slightly hypo- to isointense compared with the spinal cord. On T2-weighted images, the areas of T1 hyperintensity may show relatively decreased signal intensity. The solid portions of a dermoid cyst are hyperintense but often heterogeneous. On CT, a dermoid cyst appears as a well-defined, well-circumscribed lesion of low attenuation. The presence of calcification or teeth can be seen on CT. Reference AJR 2000; 174:874-875.

General Anatomic Area:

Lumbar

Secondary Anatomic Area:

N/A

Disease Category:

Congenital

Contributor:

Erin Simon, MD

Date:

02/01/2006

Difficulty Level:

Medium

Pathology Confirmed?:

Yes
Click here for more info

ACR Category Number:

N/A

Keywords:

inclusion cyst, lipoma,dermoid