A Congenital Spinal Epidermoid Cyst.

Abstract

A 73-year-old female with unresolved digestive complaints was referred to our department for CT imaging of the abdomen. Unexpectedly, an oval-shaped, well delineated, intramedullary located mass was found in the spinal canal at the level of the vertebra D11 and D12. On CT imaging the mass is hyperdense to CSF, shows intramural calcification and minimal to no contrast enhancement (Fig. 1A). Proximal to the spinal mass there is a longitudinal split in the spinal cord, diastematomyelia, associated with a congenital block vertebra and hemivertebra at the level of D9–D10 (Fig. 1B). There is also an unfused spinous process of D9 and D10, an anatomical variant which is part of the spectrum of spina bifida occulta (Fig. 1C). The patient has no symptoms of low back pain and no abnormalities in the neurological clinical examination. MR imaging is required for further differentiation of the mass and shows a well-defined lesion without perilesional edema, with hyperintense signal on T1 weighted images (Fig. 2A), inhomogeneous, isointense to hypointense signal on T2 weighted images (Fig. 2B) and no significant enhancement after contrast administration. For further differentiation diffusion weighted imaging (Fig. 3A) was performed and revealed diffusion restriction with corresponding low intensity on ADC map (Fig. 3B) in the entire mass, except in the region of calcification. These findings, in association with the spinal malformations (spina bifida, diastematomyelia, block vertebra and hemivertebra) are highly specific for a congenital spinal epidermoid cyst. The diastematomyelia is best shown on the coronal T2 weighted image in Fig. 4.