Nervous System Disorders
Incidence: 0.5% of primary intracranial neoplasms; 2% of intracranial tumors before age 15
Histo: mostly benign; occasionally containing highly malignant primitive elements
Location: pineal + parapineal region >floor of 3rd ventricle >posterior fossa >spine (associated with spina bifida)
- heterogeneous midline lesion, occasionally homogeneous soft-tissue mass (DDx: astrocytoma)
- contains fat + calcium
- hydrocephalus (common)
Pineal Teratoma
= benign tumor containing one / all three germ cell layers (pineal region most common site of teratomas)
Incidence: 15% of all pineal masses; 2nd most common tumor in pineal region
Age:<20 years; M÷F = 2÷1 to 8÷1
- Parinaud syndrome; hypothalamic symptoms
- headache, somnolence (related to hydrocephalus)
Histo:
- mature teratoma = fully differentiated tissue
- ectoderm: skin + skin appendages
- mesoderm: cartilage, bone, fat, smooth muscle, skeletal muscle
- endoderm: respiratory + enteric epithelium
- immature teratoma = complex mixture of fetal-type tissues from all 3 germ layers + mature tissue elements
- teratoma with malignant transformation of mature tissues
Location: pineal, parapineal, suprasellar, 3rd ventricle
- well-defined rounded / irregular lobulated extremely heterogeneous multiloculated mass of fat, cartilage, hair, linear / nodular calcifications + cysts
- Fat is absent in all other pineal tumors!
- may show heterogeneous / rimlike contrast enhancement (limited to solid-tissue areas)
Angio:
- elevation of internal cerebral vein
- posterior displacement of precentral vein
CT:
- heterogeneous mass with fat, calcification, cystic + solid areas
MR:
- variegated appearance on all pulse sequences:
- hyperintense areas of fat on T1WI with chemical shift artifact
- variable signal intensity on T1WI due to calcifications
- iso- to hypointense soft-tissue component
- enhancement of soft-tissue component
Cx: chemical meningitis with spontaneous rupture