Embryonal tumor with multilayered rosettes: a report of a rare case

Abstract

The authors report a case of an embryonal tumor with multilayered rosettes (ETMR) in an 18-month-old female infant who presented with gait imbalance and progressive left-sided weakness for 2 months. ETMR is a rare small round blue cell aggressive tumor of the central nervous system characterized by the amplification of the C19MC region on chromosome 19 (Chr19q13.42). This report in detail the clinical-radiologic and histopathological workup and diagnosis. Because ETMRs are newly described rare pediatric central nervous system tumors with only a few reported cases, we aim to document this typical case to add to the existing data on these tumors.

Figure 1.

Non-enhanced CT of the brain (a) axial and (b) coronal images show an isodense mass (arrows) in the right side of the pons extended into the right middle cerebellar peduncle with mass effect and distortion of the fourth ventricle.

Figure 2.

Brain MRI images demonstrate a right-sided pontine mass extending to the right middle cerebellar peduncle with mass effect on the fourth ventricle. The tumor is hypointense on T ₁WI (a) and hyperintense on both T ₂WI (b) and FLAIR (c) with minimal enhancement after contrast administration (d). FLAIR, fluid attenuation inversion recovery; T ₁WI, T ₁ weighted imaging; T ₂WI, T ₂ weighted imaging;

Figure 3.

Coronal T2 MRI images of the same hyperintense lesion on the right side of the pons with mass effect on the brain stem and fourth ventricle.

Figure 4.

Axial MRI images show mild restricted diffusion. The tumor is mildly hyperintense on the diffusion-weighted image (a) and hypointense on the ADC map (b). ADC, apparent diffusion coefficient.

Figure 5.

MR perfusion (rCBV) shows high relative cerebral blood volume in the pontine mass. rCBV, relative cerebral blood volume.

Figure 6.

Selected images of histopathology examination show (a) the tumor consists of small round blue cells with scanty cytoplasm and indistinct cell borders. It exhibits dense cellular areas (left half of the field) and paucicellular areas (right half of the field). Multilayered rosettes (arrow) are scattered (H&E, X200), (b) the tumor is negative for GFAP. Scattered reactive astrocytes are noted focally in the background (GFAP, X200), (c) the tumor cells are diffusely positive for CD56; in keeping with the neural nature of the neoplasm (CD56, X200), and (d) INI1 shows normal nuclear reactivity, excluding the possibility of Atypical Teratoid Rhabdoid Tumors (INI-1, X200).