Malignant Transformation of Grade II Ependymoma in a 2-Year-Old Child: Case Report

Abstract

Ependymomas are central nervous system neoplasms that account for a third of all posterior fossa tumors in children. The most common location for infratentorial ependymoma is within the fourth ventricle. We present a case report of malignant transformation of an infratentorial grade II ependymoma in a 2-year-old child who presented with vomiting and visual disturbance. An infratentorial brain tumor in the left cerebellar area was totally removed, and the initial pathologic diagnosis was grade II ependymoma. The tumor recurred aggressively 1 year later; subtotal removal and adjuvant chemotherapy were performed. After a second operation, a histopathologic study was performed. The second specimen was defined as a grade III anaplastic ependymoma. Transformation to grade III anaplastic ependymoma is possible for a grade II ependymoma but very rare. The diagnosis of the anaplastic variant of intracranial ependymomas is difficult. Surgical treatment remains the mainstay of the treatment for all cases. Ependymomas in young infants have a worse prognosis than older children, so we need individual clinical evaluation and close follow-up of such cases. This article highlights the requirement of a close follow-up for grade II ependymomas for anaplastic transformation.

Keywords: brain; central nervous system; ependymoma; malignant transformation; neoplasm.

Fig. 1

Axial initial magnetic resonance imaging scans show posterior fossa mass filled in fourth ventricle (A) with nonhomogeneous slight contrast enhancement (B). Severe hydrocephalus can be seen with temporal horn filling secondary to the obstruction of the fourth ventricle. Postoperative axial (C) and coronal contrasted images (D) show complete resection of the mass with opening of the fourth ventricle and relaxation of the temporal horns. The shunt valve can be seen subcutaneously on axial images.

Fig. 2

Postcontrast axial (A) and coronal (B) images show regrowth of the mass lesion with strong contrast uptake. Fourth ventricle and brainstem compression with attachment of the tentorium can be seen.

Fig. 3

Inıtial microscopic evaluation of the case after first operation. (A) Moderately cellular tumor composed of monomorphic cells with round to oval nuclei containing “salt and pepper” pattern of chromatin. Radially arranged ependymal cell processes become thinner toward the vascular wall leaving an acellular zone around the blood vessel, called “perivascular pseudorosette,” a key histologic feature for ependymoma (hematoxylin and eosin [H&E] ×100). After the second operation (B) abundant endothelial proliferation, microvascular proliferation, hypercellularity with nuclear hyperchromasia, pleomorphism, numerous mitoses, and pseudopalisading necrosis warrants a diagnosis of anaplastic ependymoma when seen throughout the lesion (H&E ×200). Moreover (C), focus of coagulative necrosis, nuclear pseudopalisading was prominent around the necrotic areas, tumor cells oriented closer to viable areas emphasizing anaplastic changes (H&E ×200). Ki-67 immunolabeling index is an independent prognostic factor and accurate predictor of outcome in patients with intracranial ependymoma (D). The index was 10% in the first operation that increased to 35% for our case in this image (Ki-67 ×200).