intraspinal cyst – epidermoid
description
cysts arising within the spinal cord, of ectodermal, mesodermal, or endodermal origin, which are non-neurenteric. there are four main categories: cystic teratomas, demonstrating cells derived from all three germ layers, usually found in a dorsal location at any site. epidermoid and dermoid cysts, commonly lumbosacral, associated with spina bifida occulta and diastematomyelia. arachnoid diverticula, representing sacculation of the leptomeninges, most frequently seen in the dorsal thoracic region. extradural cysts, lined by dural epithelium, thought to originate from diverticula of the dura, found most commonly in the lower thoracic region.
diagnosis
to date no non-neurenteric intraspinal cyst has been reported to have been diagnosed prenatally. the visualisation of an intraspinal cyst is certainly possible with high resolution ultrasound.
differential diagnosis
the principal diagnoses to exclude would be: neurenteric cysts, which would be implied by communication or extension of the cyst ventrally, or by associated defects of the vertebral column or diaphragm. more extensive sacculations of meningeal or neural tissue due to other aetiologies, such as myelocystocele or spina bifida.
sonographic features
isolated small intraspinal cysts with no external communication.
may be associated with spina bifida or diastematomyelia.
associated syndromes
- distichiasis- lymphedema