Excerpta Extraordinaire

Excerpta #:  EE-20

Imaging findings of Atypical Teratoid / Rhabdoid tumor in a 11-Year Old Boy

H Nakamura1, T Suzuki1, M Uchida2, M Doi3, M Takagi3, Y Tanaka2, Y Nakajima2 ,

St. Marianna University of Medicine, Radiology1 and Neurodsurgery 2 and Pahtology3 Kawasaki Japan.

Disclosures

The authors do not have a financial

relationship with a commercial

organization that may have a direct

or indirect interest in the content.

Purpose

Atypical teratoid / rhabdoid tumors (AT/RT) are

rare aggressive neoplasms occurring in

children younger than 2 years of age at the

infratentorial. We demonstrate an atypical

case of supratentorial AT/RT in a 11-year-old

boy.

History

. A 11-year-old boy came to our

hospital complaining of mild

headache and nausea, which had

been continued for a month.

CT

CT shows a large heterogeneous mass in the left frontal lobe, which contains two parts of iso density on the ventral side and low density on the dorsal side. Due to mass effect, ventricle , especially on the left side, is obliterated. Black arrow indicates small high density suggesting calcification.

DWI FLAIR

Axi / Cor T2 WI

T1WI Gd T1WI

Cor G ｄ T1WI Cor T2*

MRS

MRI findings

Solid part (yellow arrow) - heterogeneous intensity on DWI, iso and high heterogeneous intensity on T2 WI and FLAIR , low and iso heterogeneous intensity on T1 WI and mild to moderate contrast enhancement on contrast images. MRS shows decreased NAA and prominent choline peak, suggesting cell membrane turn over.

Necrotic or cystic part - low intensity on DWI and T1 WI, high signal on T2 WI, and no contrast enhancement

Calcification and hemorrhage ( white arrow on T2*)

Imaging findings

Large mass with solid and cystic component.

Calcification and hemorrhage

High choline peak.

Differential diagnosis

Pilocytic astrocytoma

Pleomorphic xanthoastrocytoma

AT/RT

Primitive Neuroectodermal Tumor (PNET)

Glioma (glioblastoma, oligodendroglioma)

(anaplastic ) ependymoma

Desmoplastic infantile ganglioglioma/astrocytoma

Surgical findings

Tumor shows well-defined margin

Solid and cystic tumor

Success of total removal

H&E stain

H&E stain on high power shows 　 large pleomorphic cells with abundant eosinophilic cell and cells with large eccentrically located nucleus, which are characteristic of rhabdoid cells.

INI-1 stain

immunohistochemistry stain for INI-1 on high power shows lack of staining (brown) in tumor cells with retention of staining in non-tumor cells.

Final Diagnosis

Atypical Teratoid / Rhabdoid tumor (AT / RT)

AT/RT

Highly malignant embryonal neoplasm (grade 4 according to the World Health Organization classification) that typically occurs in children aged <3 years and 6.7% of CNS neoplasm children aged < 3years1

Most often reported as infratentorial2, 3

Age and localization - our case

Older than 10years -12%2, 9.1%3

Adult onset almost 30 cases were reported and they favor the supratentorial4

Some reports show supratentorial is more prevalent or comparative 2, 5

Pathology

Characteristic “rhabdoid” phenotype ( large immature rhabdoid cells) are helpful for the diagnosis of AT/RT if present, however are not always seen. Pathologically , AT/RT has considerable overlap with medulloblastoma/PNET

Cytogenetic evaluation of CNS AT/RT and renal AT/RT has revealed deletions and mutations of the INI1 locus in chromosome 22

INI1 thought to represent a tumor suppressor gene

The immunohistochemical reagent for INI1 fails to stain the nuclei of tumor cells with INI1 mutations

Differential diagnosis

Only imaging findings can not distinguish from other high-grade tumors

Thick heterogeneous enhancing wall surrounding a central cyst or cysts is the key feature in differentiation from others6

Discussion

The imaging feature is typical findings of AT/RT

Supratentorial location and the age older 10 years are not typical, but not very rare

Conclusion

When we see the supratentorial solid

and cystic tumor even aged >10

years , differential diagnosis

should include AT/RT

References

1. Buscariollo DL, Park HS, Roberts KB, et al. Survival outcomes in atypical teratoid rhabdoid tumor for patients undergoing radiotherapy in a Surveillance, Epidemiology, and End Results analysis. Cancer 2012;118:4212-4219

2. Meyers SP, Khademian ZP, Biegel JA, et al. Primary intracranial atypical teratoid/rhabdoid tumors of infancy and childhood: MRI features and patient outcomes. AJNR American journal of neuroradiology 2006;27:962-971

3. Warmuth-Metz M, Bison B, Dannemann-Stern E, et al. CT and MR imaging in atypical teratoid/rhabdoid tumors of the central nervous system. Neuroradiology 2008;50:447-452

4. Han L, Qiu Y, Xie C, et al. Atypical teratoid/rhabdoid tumors in adult patients: CT and MR imaging features. AJNR American journal of neuroradiology 2011;32:103-108

5. Jin B, Feng XY. MRI features of atypical teratoid/rhabdoid tumors in children. Pediatric radiology 2013;43:1001-1008

6. Au Yong KJ, Jaremko JL, Jans L, et al. How specific is the MRI appearance of supratentorial atypical teratoid rhabdoid tumors? Pediatric radiology 2013;43:347-354