Atypical teratoid-rhabdoid tumour: A case report

A 1-year-old male patient with persistent vomiting and weight loss since a month ago. A brain MRI is ordered.

A contrast-enhanced MRI examination is performed, showing a mass in the posterior fossa located intra- and extra-axially, centred on the inferior aspect of the left middle cerebellar peduncle, with extension to the fourth ventricle and cerebellopontine angle. It causes mass effect with deviation of the cerebellar hemisphere to the left and the brain stem to the right anterolateral.

It shows a hypointense mass on T1 with heterogeneous enhancement (Figure 1), heterogeneous signal on T2 and FLAIR with the presence of multiple cystic-necrotic foci (Figure 2), and significant restricted diffusion with hyperintensity on diffusion-weighted images (DWI) correlating with clearly low apparent diffusion coefficient values (ADC), which indicates high cellularity (Figures 3a and 3b). Presents multiple intratumoural signal void foci in susceptibility-weighted imaging (SWI) that translates intralesional bleeding (Figure 4).

Atypical teratoid-rhabdoid tumour (AT/RT) is a highly malignant and rare neoplasm of the central nervous system (CNS), usually affecting very young children (median age is less than 2–3 years) [1]. These tumours can have any location in the CNS, whether supratentorial or infratentorial, with a preference for the cerebellopontine angle [2]. AT/RT was not recognised as a distinct entity until the 1980s, due to its resemblance to other tumours. Although its recognition has increased, published data remains mostly limited to small case series [3].

Presenting symptoms depend on the location and size of the tumour but may include headaches, nausea, vomiting, extremity weakness, lethargy, extraocular muscle weakness, and facial paralysis [4].

Imaging, particularly magnetic resonance imaging (MRI), is crucial in paediatric brain tumour evaluation. MRI reveals AT/RT characteristic features to carry out a diagnostic approach. Differentiating AT/RT from other tumours is essential for accurate diagnosis and treatment planning [1,4].

Distinguishing AT/RT on MRI requires considering specific imaging features. This tumour typically presents as a heterogeneous mass with necrosis and haemorrhage, displaying heterogeneous enhancement and diffusion restriction, often with leptomeningeal dissemination. Differential diagnosis from other tumours like medulloblastoma relies on these characteristics [4,5].

Confirmation of the diagnosis generally requires a biopsy of the tumour for pathological analysis. Histologically, AT/RT demonstrates a combination of primitive neuroectodermal, mesenchyma, and epithelial elements, with characteristic loss of the INI1 protein expression [6].

The therapeutic options include aggressive treatment approaches with surgery, radiotherapy, and chemotherapy [2,6,7]. However, the most important component in the treatment is radiotherapy, since starting it early during the first postoperative month increases survival rates [2,7].

The prognosis of patients with an AT/RT is poor, with high rates of recurrence and mortality, especially in patients younger than 3 years of age, with a survival time that averages 15 months in children and 38 months in adults [1,5].

Written informed patient consent for publication has been obtained.