====== Intracranial neurenteric cysts ======

===== General information =====

Rare, most common in [[posterior fossa]]. Initially, may be difficult to rule out [[metastasis]] from an extremely well-differentiated primary [[adenocarcinoma]] of unknown origin (absence of progressive disease suggests NEC). 

Locations:

1. [[posterior fossa]]

a) [[cerebellopontine angle]] (CPA): usually intradural, extraaxial (case report of extradural lesion
with bone destruction)

b) in midline anterior to [[brainstem]]

c) [[cisterna magna]]

2. [[supratentorial]]: only 15 case reports as of 2004. 

Locations: [[suprasellar]] (possible confusion with [[Rathke’s cleft cyst]]), frontal lobe intraparenchymal, [[quadrigeminal plate]] region, duralbased extra-axial. Source of [[endoderm]] is controversial since the primitive foregut extends cranially only to the [[midbrain]].

Theory: [[colloid cyst]]s, Rathke cleft cysts, and supratentorial NECs may all arise from remnants of Seesel’s pouch, a transient endodermally derived diverticulum of the cranial end of the embryonic foregut.

===== Histology =====

Most are simple [[cyst]]s lined by cuboidal-columnar [[epithelium]] and [[mucin]]-secreting goblet cells. Less common types of epithelium described include stratified squamous and pseudostratified columnar, and ciliated epithelial cells. Mesodermal components may be present, including [[smooth muscle]] and adipose tissue, and some have called these [[teratoma]]tous cysts, not to be confused with teratomas, which are true germinal cell neoplasms. Maybe histologically identical to [[colloid cyst]]s.

===== Clinical =====

Most commonly present during the first decade of life.

Pain or myelopathy from the intraspinal mass are the most common presentations in older children and adults. Neonates and young children may present with cardiorespiratory compromise from an intrathoracic mass, or with cervical spinal cord compression. Meningitis may occur from the fistulous tract, especially in newborns and
infants.

===== Imaging =====

Intracranial NEC:

● CT: usually low density, nonenhancing

● T1WI MRI: isointense or slightly hyperintense to CSF (may be hyperintense if there are blood
products). T2WI isointense to CSF. Nonenhancing

===== Histology =====

Most are simple cysts lined by cuboidal-columnar epithelium and mucin-secreting goblet cells.
Less common types of epithelium described include: stratified squamous and pseudostratified columnar,
and ciliated epithelial cells. Mesodermal components may be present, including smooth
muscle and adipose tissue, and some have called these teratomatous cysts, not to be confused
with teratomas, which are true germinal cell neoplasms. May be histologically identical to colloid
cysts.

===== Treatment =====

Spinal NEC

Surgical removal usually reverses the symptoms. Recurrence is uncommon with complete removal
of cyst wall.

Intracranial NEC

Capsule adherent to brainstem may prevent complete resection, which predisposes to delayed recurrence.
Apparently successful treatment by evacuation of contents and marsupialization has been
reported (5 cases, mean follow-up: 5 yrs). Incomplete removal requires long-term follow-up.
Hydrocephalus is shunted if indicated.