SPR unknown case #30 -- Final

Amy Tang, BS MS3

Arie Franco, Md, PhD

Ramon E. Figueroa MD, FACR

Medical College of Georgia

Keywords

SPR unknown 30 ATRT atypical teratoid rhabdoid tumor


Publication Date: 2010-05-26

History

6-month-old female with increased head circumference over two months, one week history of head tilts favoring the right side, and acute onset of emesis, diarrhea, and lethargy.

Findings

CT of the brain (image 1): A large heterogeneous mass in the right cerebral hemisphere with associated hemorrhage and calcification. Hydrocephalus seen with significant subfalcine herniation.

MRI of the brain: Flair (images 2 & 3), T2 (image 4), DWI (images 5&6), and post gad (image 7)

A large supratentorial lesion in the right cerebral hemisphere, which demonstrates a heterogeneous appearance and enhancement with multiple areas of necrosis and hemorrhage. It is producing compression of the right lateral ventricle as well as right to left midline shift. Increased diffusion restriction noted.

A lesion of the upper and anterior portion of the cerebellar vermis, which extends transtentorially toward the left side to the area adjacent to the left lateral ventricle. This lesion demonstrates a large cystic portion with fluid.

There is a significant active noncommunicating hydrocephalus.

Diagnosis

Atypical teratoid/rhabdoid tumor

DDx

Primitive neuroectodermal tumor (PNET), medulloblastoma, ependymoma, choroid plexus carcinoma

Discussion

Atypical teratoid/rhabdoid tumors (ATRTs) are rare childhood intracranial tumors that most commonly present before two years of age. This neoplasm is defined by the presence of rhabdoid cells and a combination of mixed cellular elements, similar to but histologically different from more familiar teratomas (1, 2). ATRT represents 1.3% of primary CNS tumors in the general pediatric population, and 6.7% in children younger than two years of age (3).

ATRT is often misdiagnosed as primitive neuroectodermal tumor (PNET), as the two present with similar clinical signs and symptoms, as well as similar radiological features. Histologically, ATRT is composed either entirely or partly of rhabdoid cells. Seventy percent also contain fields of typical PNET alone or in combination with mesenchymal and/or epithelial elements (1).

The typical presenting features of ATRT are related to the location and size of the lesion. These tumors usually occur in the cerebellum, with the majority occurring in the cerebellopontine angle; less common areas of involvement are supratentorial, pineal, spinal, and multifocal (2). Generally, patients present with classic symptoms of increased intracranial pressure, such as headache, vomiting, lethargy, and failure to thrive. Additionally, cerebellar involvement may cause ataxia and gait disturbance, while tumors involving the cerebellopontine angle may cause cranial nerve VI and VII palsies (1, 2).

The imaging modality of choice for ATRT is MRI; this tumor classically appears as a bulky, heterogenous, and solid cystic mass in a child younger than two years of age (4). In contrast to PNET, which is more commonly a midline lesion, ATRT tends to occur off-midline and have more readily visible calcification and greater cyst formation. However, these characteristics are variable in both tumor types and the exact location of the neoplasm may be difficult to characterize due to large tumor size (4,5).

Definitive diagnosis of ATRT rests ultimately on immunohistochemical studies: the majority of these tumors are positive for epithelial membrane antigen, vimentin, and smooth-muscle actin, and are negative for markers for germ-cell tumors, differentiating them from PNET (1).

References

  1. Rorke LB, Packer RJ, Beigel JA. Central nervous system atypical teratoid/rhabdoid tumors of infancy and childhood: definition of an entity. J Neurosurg, 1996 Jul;85(1): 56-65.
  2. Fenton LZ, Foreman NK (2003) Atypical teratoid/rhabdoid tumor of the central nervous system in children: an atypical series and review. Pediatric Radiology, 33(8): 554-8
  3. Rickert CH, Paulus W (2001) Epidemiology of central nervous system tumour in childhood and adolescence based on new WHO classification. Childs Nerv Syst 17:503–511
  4. Dang T, Vassilyadi M, Michaud J, Jimenez C, Ventureyra EC (2003) Atypical teratoid/rhabdoid tumours. Childs Nerv Syst 19:244–248
  5. Arslanoglu A, Aygun N, Tekhtani D, Aronson L, Cohen K, Burger PC, Yousem DM (2004) Imaging findings of CNS atypical teratoid/rhabdoid tumours. Am J Neuroradiol 25:476–480

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