Primary atypical teratoid/rhabdoid tumor of central nervous system in children: a clinicopathological analysis and review of literature in China

Abstract

Atypical teratoid/rhabdoid tumor (AT/RT) is a very rare and highly malignant embryonal tumor in the central nervous system (CNS). Five patients (4 girls and 1 boy) with AT/RT were treated in our hospital. The clinical histories, symptoms, neuroimaging aspects, therapies, histological and immunohistochemical findings and follow-up information were reviewed. The patients ranged from 8 to 40 months with a mean age of 20.6 months. One tumor was located in the spinal cord, two in cerebellum and two in the pineal region. The imagings of the tumors resemble medulloblastomas. Pathological examinations showed that one patient had medulloblastoma differentiation, one had choroid plexus carcinoma differentiation, and one had mesenchymal components. Immunohistochemical staining showed that all of the tumors lost the nuclear expression of integrase interactor 1 (INI1), and were positive for Vimentin, S-100 protein and epithelial membrane antigen. One case with no recurrence after 24 months may have benefited from radical excision and postoperative radiotherapy. The other 4 patients died 8, 4, 1 and 1-month respectively after operation without radiotherapy. The diagnosis of AT/RT depends on full sampling, careful observation the morphological characteristics and INI1 examination, even when the tumor are presented in uncommon sites, such as the spinal cord and the pineal region.

Keywords: Atypical teratoid/rhabdoid tumor; cerebellum; integrase interactor 1; pineal gland; spinal cord.

Figure 1

Magnetic resonance images of atypical teratoid/rhabdoid tumor. A: T1-weighted midline sagittal image from case #1 shows an intramedullary tumor of C2-T2. B: T2-weighted image from case #2 demonstrates abnormal signal in the cerebellum and relative intermediate signal intensity of the lesion. C: T1-weighted image from case #3 shows Cerebellar mass and enhance with contrast. D and E: Images of brain from case #4, #5 show an intermediate signal intensity tumor respectively on the pineal and protruding into the ventricular lumen.

Figure 2

Sections from case #1-5 stained with hematoxylin and eosin (A-E). (A) Case 1. The atypical cells with dark nucleus diffuse distributed in myxoid stroma in some regions of the tumor. (B) Case 2. Tumor cells with a sheet-like pattern of growth, vesicular chromatin, prominent nucleoli. A few cells were eosinophilic plenty cytoplasm with eccentric nuclei. (C) Case 3. There were some papillary structures in some regions of the tumor. (D) Case 4. The mesenchymal component with short spindle tumor cells, focal myxoid stroma in some regions of the tumor. (E) Case 5. The tumor cells were very large and atypical oval nuclei with vesicular chromatin and prominent nucleoli. A few cells were eosinophilic plenty cytoplasm with eccentric nuclei. A few cells were of clear cytoplasm. Original magnification: × 100 (A), × 200 (B), × 100 (C), × 100 (D), × 200 (E).

Figure 3

IHC from cases 1-5 (A-E) stained for SMARCB1/INI1. SMARCB1/INI1 reactivity is absent in tumor cells but retained in endothelial cells and infiltrating inflammatory cells. Original magnifications, ×100 (A), × 200 (B), × 200 (C), × 40 (D), × 200 (E).