Intracranial Mass
Paula J. Woodward, MD
DIFFERENTIAL DIAGNOSIS
Common
Intracranial Hemorrhage
Rare but Important
CNS Tumors
Teratoma
Astrocytoma
Craniopharyngioma
Choroid Plexus Papilloma
Lipoma
Primitive Neuroectodermal Tumor
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Doppler critically important in evaluating any intracranial mass
Intracranial hemorrhage (ICH) will show no flow
Tumors will have vascular flow
Tumors may have areas of hemorrhage; important to sample entire mass
Follow-up studies helpful
ICH will evolve over time with developing areas of encephalomalacia and porencephaly
Many tumors will show rapid growth rates
MR very helpful in characterizing intracranial masses
Sensitive for blood products
Better anatomic evaluation for extent of hemorrhage or mass
Considerable overlap in appearance of many tumor types (teratoma, astrocytoma, craniopharyngioma, primitive neuroectodermal tumor)
Differentiation often not possible or even necessary
Universally dismal prognosis
Most are supratentorial
Precise point of origin can often not be determined
May extend through skull base into oral cavity
May cause gross distortion of cerebral architecture
Hydrocephalus common
Polyhydramnios secondary to decreased swallowing from hypothalamic dysfunction
Important to recognize lipomas and choroid plexus papillomas as prognosis is substantially better
Helpful Clues for Common Diagnoses
Intracranial Hemorrhage
Bleeds may be intraparenchymal, subependymal, intraventricular, or subdural
Always use Doppler to confirm no flow in “mass”
Look for vascular malformation as potential cause of bleed
Typically present as a non-perfused, echogenic, intracranial “mass”
Most are supratentorial
Posterior fossa uncommon
Intraventricular hemorrhages may appear as an irregular, bulky choroid plexus
Also look for echogenic, irregular ependyma as residual sign of earlier bleed
Hemorrhage usually extensive when diagnosed in utero
Normal intracranial landmarks often obscured
Initially clot is hyperechoic
Becomes hypoechoic with time
Look for evolving areas of encephalomalacia/porencephaly
Hydrocephalus commonly develops
MR excellent for evaluating for blood products
T1WI high signal (methemoglobin)
T2WI low signal
Helpful Clues for Less Common Diagnoses
Teratoma
Most common tumor (approximately 50% of all fetal CNS tumors)
Complex masses with cystic and solid components
Typically midline location
Calcifications most specific finding but not always present
May fill entire cranial vault and extend through skull base into mouth
Astrocytoma
Solid tumors
Arise in cerebral hemispheres
Can be seen in the setting of tuberous sclerosis
Most common at foramen of Monro
Craniopharyngioma
Arise from Rathke pouch, an ectodermal diverticulum from roof of mouth
Suprasellar midline mass
Frequently calcify
Indistinguishable from teratoma
Choroid Plexus Papilloma
May occur anywhere in ventricular system
Lateral ventricle most common
Well-defined, lobular, hyperechoic mass
Hydrocephalus from over production of cerebral spinal fluid (CSF)
Often rapid onset
Mass may also obstruct ventricle causing asymmetric enlargement
Lipoma
Well-defined, echogenic mass
Midline or lateral ventricles
Up to 50% of midline lipomas associated with agenesis of the corpus callosum
May be multiple
Primitive Neuroectodermal Tumor
Highly malignant small-cell tumor
Derive from neural crest
Extremely rapid growth
Indistinguishable from other intracranial tumors
Other Essential Information
Findings in agenesis of the corpus callosum
Absent cavum septi pellucidi
Elevation of 3rd ventricle creating “trident” shape in coronal plane
Colpocephaly (teardrop-shaped ventricles)
Midline lipoma or cyst
Alternative Differential Approaches
Intraventricular masses
Choroid plexus cyst
Very commonly seen in normals but does have an association with trisomy 18
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