Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 58, Num. 6, 2010, pp. 928-932

Neurology India, Vol. 58, No. 6, November-December, 2010, pp. 928-932

Topic of the Issue: Case Report

Advanced magnetic resonance imaging with histopathological correlation in papillary tumor of pineal region: Report of a case and review of literature

V Vaghela¹, N Radhakrishnan², VV Radhakrishnan², G Menon³, C Kesavadas¹, B Thomas¹

¹ Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
² Department of Pathology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
³ Department of Neurosurgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
Correspondence Address: B Thomas, Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala - 695 011 , India, drbejoy2002@yahoo.com

Date of Acceptance: 04-Oct-2010

Code Number: ni10259

PMID: 21150061
DOI: 10.4103/0028-3886.73750

Abstract

Keywords: DWI, MRI, magnetic resonance spectroscopy, papillary tumor of the pineal region, perfusion

Introduction

Papillary tumor of the pineal region (PTPR) is a recently described distinct clinicopathological entity with limited evidence on its clinical behavior, natural history, and characteristic imaging features. ^[1] These tumors are thought to arise from the specialized ependymocytes of the subcommissural organ located in the lining of the posterior commissure. ^[2] Histologically, PTPR demonstrates a unique assortment of epithelial, ependymal, and neuroendocrine features. ^[3] According to descriptions in radiological literature, these tumors are hyperintense on T1W images and may show few cystic areas. ^[4],[5] This may resemble pineocytoma on imaging. ^[6] We describe advanced MR imaging features like perfusion, diffusion, and spectroscopic findings in a histologically proven case of PTPR. We also review the literature on the same.

Case Report

An 18-year-old girl presented with history of recurrent right temporo-parietal headache associated with nausea without any diurnal variations. She also complained of intermittent double vision especially on looking to the left. The neurological examination was unremarkable.

MR imaging on a 1.5T scanner (Avanto-SQ engine, Siemens, Erlangen, Germany) revealed a mass at the pineal region, which was extending into the posterior third ventricle and was compressing the tectal plate from above. The mass was hyperintense on non-contrast T1-weighted images with presence of a few cystic areas, which were hypointense on T1 and FLAIR images. The mass showed heterogeneous contrast enhancement. The solid portions of the mass showed minimal restriction on diffusion weighted images. The average apparent diffusion coefficient of the lesion was 0.812 Χ 10 ^-3 mm ² /s. It was showing a solitary focus of blooming on susceptibility weighted imaging, which might be due to calcification/bleed. Proton MR spectroscopy revealed increased choline, increased myo-inositol and decreased N-acetyl aspartate peaks with a small lactate peak. On perfusion imaging, lesion showed significantly elevated relative cerebral blood volume (rCBV) and relative cerebral blood low (rCBF) of 6-9 times compared to normal white matter [Figure - 1]. The patient underwent ventriculostomy and surgical resection of the mass.

Hematoxylin and Eosin stained sections of the tissue obtained showed a cellular neoplasm exhibiting papillary areas as well as solid growth pattern [Figure - 2]. Papillary areas were composed of cells with moderate amount of eosinophilic cytoplasm, round to oval nuclei, whereas the solid areas showed cells with eosinophilic as well as clear cytoplasm. Neither mitotic figures nor necrosis was seen. In our case, the sections were stained for cytokeratin (Dako, pre-diluted), S-100 (Dako, 1 : 100), neuron-specific enolase (NSE, Dako, 1 : 50), glial fibrillary acidic protein (GFAP, Novacastra, 1 : 100), and epithelial membrane antigen (EMA, Dako 1 : 100) [Table - 1].

The neoplastic cells were diffusely immunoreactive for cytokeratin and S-100 antibodies. Isolated and small clusters of cells were immunoreactive for neuron-specific enolase. Immunohistochemistry for epithelial membrane antigen and GFAP were negative. The tumor morphology and immunohistochemical profile was typical of PTPR.

Discussion

Wide range of neoplasm occurs in the pineal region and they constitute diagnostic challenge in both radiological and pathological point of view. 'Papillary tumors of the pineal region' has been added recently to this list, which is a rare tumor, with uncertain prognosis, and a possible high risk for local recurrence. ^[7]

Jouvet et al. in 2003 described for the first time, papillary tumor of the pineal region, which was formally recognized as a distinct entity by the 2007 WHO Classification of Brain Tumors. ^[8] In 2004, Shibahara et al. confirmed the origin of these tumors from specialized ependyma of the subcommissural organ (SCO) by showing transthyretin expression of the tumor, as transthyretin is one of the proteins presumed to be secreted by human SCO. ^[9],[10] The SCO is an ependymal brain gland located in the third ventricle, at the entrance of the third ventricle, and secretes glycoproteins into the ventricular cerebrospinal fluid. ^{[11],[12],[13]} The histopathology of papillary tumors of the pineal region (PTPR) closely resembles that of ependymomas and choroid plexus tumors as they display histopathologic features of ependymal differentiation from which it can be differentiated by absent staining for epithelial membrane antigen, Kir7.1 and staniocalcin-1 as well as the presence of distinct MAP-2 immunoreactivity. ^{[14],[15],[16]} Other tumors of the pineal region that may exhibit papillary features include metastatic papillary carcinomas, pineal parenchymal tumors, and meningiomas. ^[17],[18]

Fevre-Montange et al. presented one of the largest series of PTPR consisting of 31 patients, and suggested five-year estimates for overall and progression-free survival of 73% and 27%, respectively. ^[19] They also noted that these tumors are characterized by frequent local recurrence and should be addressed with radiotherapy. Clinically, age of occurrence is wide, ranging from 5 to 66 years with mean age of 29 years. From available reports we found slight female predominance of incidence with peak incidence occurring at different age group in male and female sex [Figure - 3]. Few reports suggest that PTPR have high risk of recurrence (72%) especially if there is residual lesion after resection. ^[20] Sato et al. reported a case with early CSF dissemination and relentless progression in spite of intensive chemotherapy and comprehensive radiotherapy. ^[21] Main clinical and radiological data of patients of reviewed articles are summarized in [Table - 2].

Very few authors have studied the MR imaging appearance of PTPR. One report has described PTPR as T1 hypointense lesion. ^[22] We found three reports which have described T1 hyperintensity of these tumors as is in our case. ^[4],[5],[21] Explanation given for T1 hyperintensity is presence of proteins and glycoproteins in the small cystic spaces seen within these tumors. ^[4] On T2-weighted images these lesions are iso to hypointense and shows inhomogeneous enhancement on post-contrast T1W images. Inoue et al. and others have reported cystic areas within these lesions as also seen in our case. ^[23],[24] In our case, solid region of the tumor shows diffusion restriction with ADC value of 0.812 Χ 10 ^-3 mm ² /s. Two reports have given the ADC value of these tumors (0.854 Χ 10 ^-3 mm ² /s; 0.60 Χ 10 ^-3 mm ² /s). ^[5],[23] Proton MR spectroscopy of these tumors showed increased choline and decreased N-acetyl aspartate peaks with a slightly increased lactate peak. We noted similar findings in addition to a high myo-Inositol peak in the present case.

To the best of our knowledge, perfusion characteristic of this tumor has not been reported previously. In this case we noted a high rCBV and rCBF. A high perfusion pattern usually corresponds to a higher grade of the tumor with few exceptions. ^{[25],[26],[27],[28]} Perfusion pattern of other pineal region tumors like germinoma can show high perfusion (rCBV ratio 4.7-4.8). Inoue et al. has observed highly significant 18 [F] fluorodeoxyglucose uptakes at the site of the lesion on PET imaging. ^[23] Sato et al. also reported a case of PTPR with intense uptake of 111 In-DTPA-pentetreotide in a young boy with rapid CSF dissemination and poor prognosis. ^[21] Thus, high tracer uptake and rCBV may imply a higher grade in view of high recurrence rate of these tumors. ^[29]

Differentiation of this tumor from other tumors of pineal region is necessary as natural history and behavior of this tumor is not yet clear and has reported high recurrence rate of this tumors. Radiological differential diagnosis of mass lesion in this region includes germinoma, pineocytoma, pineoblastoma, and teratoma. The points for differentiation between these lesions from PTPR are given in [Table - 3]. T1 hyperintensity and higher perfusion values may help in differentiating PTPR from other pineal region tumors. From the available literature, these tumors appear well-defined and usually less than 4 cm in size. ^[30],[31] These features may help differentiating these tumors from pineoblastoma and glioma, which are usually infiltrative and larger in size.

Treatment guidelines of these tumors are not yet well established due to limited case data. ^[32],[33] The biological behavior of PTPR is variable and may correspond to WHO grades II or III, but precise histological grading criteria remain to be defined. ^[34]

Our study is limited by single case report; however, larger imaging study with more number of patients and long-term follow-up may be required for developing MR diagnostic criteria and grading of these tumors.

References

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