Pediatrics
CNS Teratoma: Midline Fat in a Young Patient
Fellowship-level neuroradiology teaching by E. Brooke Schrickel, MD. Open this topic in the interactive reading room →
Core clinical idea
The recognizable signature is a midline, heterogeneous, multi-tissue mass containing macroscopic fat in a young patient — fat in the right midline location puts teratoma at the top. Recognize the signature, predict the consequence (third-ventricular masses cause obstructive hydrocephalus and raised ICP), report the surgically-relevant extent (hidden presacral component in sacrococcygeal lesions), and resist grading by enhancement, which is present in all teratoma grades.
Bottom line
Midline + heterogeneous + fat = teratoma in a child — anchor by location, report the hydrocephalus or the hidden presacral extent, and don't grade it by enhancement.
Core workstation questions
- Is this mass midline, heterogeneous, and does it contain macroscopic fat?
- Is a different entity the better answer for this location (suprasellar = craniopharyngioma first)?
- Does the lesion go black on T2, triggering the aneurysm/dermoid/lipoma/craniopharyngioma differential?
- Is there obstructive hydrocephalus, and at what level?
- For a sacrococcygeal lesion, how much is presacral/intrapelvic versus external, and are there anorectal/GU/cord anomalies?
- Are tumor markers (AFP, beta-hCG) indicated to assess a malignant component?
What changes reporting / management
- Report a midline heterogeneous mass with macroscopic fat and calcification as consistent with teratoma.
- Report the obstructive hydrocephalus and level of obstruction for third-ventricular/pineal/suprasellar masses, not just the mass, since that triages the patient.
- Do not imply malignancy from enhancement alone — capsular/heterogeneous enhancement occurs across mature, immature, and malignant teratomas.
- Prompt the team that serum/CSF tumor markers help characterize a malignant component (an imaging-adjacent recommendation, not an imaging grade).
- For sacrococcygeal teratoma, give the surgeon the presacral/intrapelvic extent (Altman framework) and report associated anorectal/genitourinary anomalies, sacral dysgenesis, cord tethering, and syrinx.
Practical traps
- Grading a teratoma by enhancement — enhancement cannot separate mature, immature, and malignant types.
- Being falsely certain of craniopharyngioma in the suprasellar region; a confident craniopharyngioma can be biopsy-proven teratoma.
- Reporting only the external component of a sacrococcygeal teratoma and missing the surgically-critical hidden presacral/intrapelvic extent.
Teaching pearls
- Midline, heterogeneous, fat-containing mass in a young patient = think teratoma.
- Macroscopic fat in a midline mass is the confirming feature.
- Suprasellar mass in a child is craniopharyngioma first — but a confident craniopharyngioma can be a teratoma.
- Black on T2? Run the list: aneurysm, dermoid, lipoma, craniopharyngioma — teratoma joins it.
- Third-ventricular teratoma -> hydrocephalus and raised ICP — report the obstruction.
- Enhancement doesn't grade a teratoma — it's present in all three types.
- Sacrococcygeal teratoma: tell the surgeon the presacral/intrapelvic extent and look for associated anomalies.
Source lectures
- Teratomas of the Central Nervous System
Educational material for radiology residents and neuroradiology fellows. Nothing here drives individual patient care, and it contains no patient data.