Pineal Anaplastic Ependymoma - A Rare Entity
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.325365
Source of Support: None, Conflict of Interest: None
Keywords: Anaplastic ependymoma, IHC, pineal ependymoma, pineal region tumorsKey Message: Although ependymoma is rare in the pineal region, it should be considered in the differential diagnosis. IHC is mandatory to differentiate from papillary tumor of pineal region.
Pineal region tumors are very rare and accounts for less than 1% intracranial space occupying lesions in adults. A wide variety of histological tumor subtypes can arise in the pineal region most common being germ cell tumor followed by pineal parenchymal tumor. Very rarely, glial tumors arise in the pineal region. It is paramount to establish a definitive histological diagnosis because their management is quite different. Ependymoma usually arises from the ependymal lining of the ventricles and spinal cord. Pineal ependymomas are extremely rare and usually arises from a specialized ependymal cells of circumventricular organs.
A 42-year-old lady presented with head ache and blurring of vision for one month. Neurological examination showed papilloedema on fundoscopy and restriction of upward gaze. MRI Brain revealed a mass in the pineal region and the region of tectal plate measuring 30 × 30 × 35 mm, hyperintense on T2/FLAIR images and hypointense on T1-weighted image enhancing with contrast [Figure 1]a. The patient underwent VP shunt initially. Four days later, midline suboccipital craniotomy and tumour excision via infratentorial supracerebellar approach were done. The postoperative period was uneventful and the patient underwent radiotherapy.
Initially, squash cytology was sent intraoperatively and showed [Figure 2]a sheets of atypical cells with round to oval nuclei with vescicular chromatin, frequent mitosis, moderate pleomorphism in a fibrillary background. At places, the tumor cells were admixed with lymphocytes, focal calcification, and prominent endothelial cell proliferation. No necrosis was seen and the possibility of high-grade glioma was suggested. The microscopic examination of routine formalin-fixed specimen [Figure 2]b showed multiple fragments of tumour tissue composed of round to oval cells with speckled nuclear chromatin and fibrillary cytoplasm with interspersed numerous blood vessels. The cells were arranged radially around the blood vessels with perivascular fibrillary processes (pseudorosettes) at places. The cells exhibited moderate pleomorphism, few multinucleated giant cells, frequent mitosis (around 12-15/10HPF), and intranuclear inclusions. There was focal calcification, myxoid change, microcystic spaces, and intratumoral hemorrhage.
Immunohistochemically, tumor cells expressed diffuse cytoplasmic membranous positivity for GFAP (glial fibrillary acidic protein) (clone -EP13) and S100 (clone-EP 32) on both nuclear and cytoplasmic positivity. For Ki67 labelling index (clone-MMI) - 42% tumour cells show positivity based on MIB-1 index [Figure 2]c and [Figure 2]d. The features were suggestive of anaplastic ependymoma (WHO Grade III).
Following surgery, radiotherapy was given and the patient tolerated well. She is being followed up as an outpatient.
Pineal gland tumor is an uncommon tumor accounting for 0.4–1% of adult intracranial tumors and 3–8% in the pediatric age group. Common neoplasm in this region being germ cell neoplasm with 40% frequency followed by pineal parenchymal tumor which accounts for approximately 20% of the cases. Glial tumors are very rare of which astrocytomas are common. Pineal region ependymomas are not very common; they usually arise from the specialized ependymal cells located in the circumventricular organs. The first case of pineal ependymoma was reported by Ringertz et al. (1954) and the second case was reported by Chor et al. (1998). So far, 12 cases of pineal ependymoma including three anaplastic ependymomas have been reported in the literature.,,,
Clinically, pineal gland tumors present with features of increased intracranial pressure, obstructive hydrocephalus, and Parinaud's syndrome. MRI brain with contrast is the investigation of choice. The definitive diagnosis of the tumor type can be made by histopathological and immunohistochemical examination of the excised tumor specimen.
Histologically, ependymomas are characterized by monomorphic cells with round to oval nuclei, speckled nuclear chromatin. The key features being pseudorosettes and true rosettes, the other features include myxoid degeneration, intratumoral hemorrhage, calcification, and microcystic changes. Our case showed all these features. The differential diagnosis of ependymoma in this region includes papillary tumor of pineal region, especially if the papillae and pseudorosettes are prominent, as both can show these features. Papillary tumor of the pineal region is a newly included entity in WHO 2016 guidelines and is characterized by eosinophilic cuboidal to columnar cells arranged in the pseudorosette in a distinctive papillary pattern and are thought to be of ependymal origin based on their ultrastructural features.
Immunohistochemically, ependymoma expresses diffused positivity for GFAP, whereas the papillary tumor of the pineal region shows only focal GFAP positivity around the vessels (perivascular). Since our case exhibited strong diffuse positivity for GFAP and negative for CK (cytokeratin), we ruled out the latter.
Anaplastic ependymoma usually has an unfavorable prognosis, high cellularity focally or throughout, nuclear pleomorphism and/or necrosis of which mitotic activity is an important criterion. In our case, MIB 1 labelling index showed around 40%. Pineal gland ependymoma on a total of 12 cases have been reported,,, of which only three cases of anaplastic ependymoma in the pineal region are reported in the literature [Table 1]., The present case is the thirteenth case of pineal ependymoma and fourth case of anaplastic ependymoma in the pineal region to be reported.
Ependymomas are usually managed by combined surgery with adjuvant radiotherapy. Our case was managed by surgery with adjuvant radiotherapy. The postoperative CECT did not reveal any mass on follow up.
This case is being presented for its rare occurrence and should be considered in the differential diagnosis of pineal tumors. Histopathology and immunohistochemistry are essential for the diagnosis and appropriate management.
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[Figure 1], [Figure 2]