Radiology Teaching Files > Case 348078

Contributed by: Children's Hospital Omaha, Radiologist, Omaha Childrens, Creighton University and UNMC, Nebraska, USA.
Patient: 1 year 1 month old female
History: One year, one month old female with vomiting and failure to thrive.

Fig. 1: Sagittal T1 precontrast. Heterogenous mass appearing to arise from 4th ventricle. High signal likely represents hemmorhage (methemoglobin) or calcification.

Fig. 2: Sagittal T1 post contrast, Partially well-circumscribed mass extending from the foramen magnum to the superior vermis, contrast enhancement superiorly and anteriorly. Mild tonsilar herniation. Hydrocephalus persists.

Fig. 3: Axial T1 precontrast. Well-circumscribed heterogenous mass in posterior fossa with high signal representing hemmorhage or calcification. 4th ventricle not visualized.

Fig. 4: Axial T1 post contrast, Well-circumscribed mass appearing to arise from 4th vent, with heterogenous contrast enhancement. Rim of low signal intensity noted anteriorly and to the right which may represent hemosiderin.

Fig. 5: Axial T2, Heterogenous signal intensity mass arising from 4th ventricle

Fig. 6: Coronal T2, Heterogenous signal intensity mass arising from 4th ventricle and involving cerebellar white matter and extending into the medulla

Fig. 7: Axial diffusion shows bright signal in periphery of solid component of tumor and low signal in hemorrhagic and/or calcified portion of tumor. Bright signal on DWI likely represents T2 shine through vs cytotoxic tissue

Fig. 8: 1 day post-op T1 precontrast. High signal intensity seen inferiorly which may represent blood product. 4th ventricle now seen.

Fig. 9: 1 day post-op T1 post contrast. Thick linear enhancement posterior resection margin, suspicious for residual tumor.

Fig. 10: 1 day post-op T2 High signal intensity medial left cerebellum representing post operative edema vs ischemia. Bilateral subdural effusions noted.

Fig. 11: 1 day post-op T1 axial precontrast

Fig. 12: 1 day post-op post contrast. Linear enhancement posterior resection margin, suspicious for residual tumor.

Fig. 13: 1 day post-op axial diffusion New hyperintensity medial cerebellum, indicating area of restricted diffusion secondary to post-operative edema vs acute ischemia

Fig. 14: Small blue cell area

Fig. 15: Rhabdoid type cells

Fig. 16: Malignant small blue cells

Fig. 17: Malignant cells with halo

Fig. 18: Large malignant cells

Fig. 19: Focal calcification

Fig. 20: Choroid plexus invasion

Fig. 21: Fibrotic area with large malignant cells
Findings: MRI shows well circumscribed mass with epicenter in 4th ventricle. Anterior rim of 4th ventricle is visible whereas posterior 4th ventricle is not visible, suggesting that mass may arise from posterior/inferior medullary velum, suggestive of medulloblastoma. Mass contains some hemorrhage or calcification and heterogenously enhances. Part of mass is bright on diffusion, suggestive of a highly cellular tumor such as PNET, medulloblastoma. Less likely, differential diagnosis would be an ependymoma or teratoid/rhabdoid tumor.
Diagnosis: Atypical teratoid/rhabdoid tumor

Medulloblastoma contains cystic/necrotic areas in 10-16% of cases. Medulloblastoma has calcifications in 13% and hemorrhage in 3%.
Atypical teratoid/rhabdoid tumor is rare with a generally poor prognosis. ATRT can have a variety of histiologic patterns, as demonstrated in this patient.


Submitted by:
Chad Eicher, M.D., Radiology Resident, Creighton University Medical Center, Sandra Allbery, M.D., and Phillip J. Silberberg, M.D, Radiology, Children's Hospital, Omaha, NE

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Additional Details:

Case Number: 348078Last Updated: 10-19-2004
Anatomy: Cranium and Contents   Pathology: Neoplasm
Modality: MR, PathologyExam Date: Access Level: Readable by all users
Keywords: posterior fossa tumor, rhabdoid tumor

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