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ORIGINAL ARTICLE
Year : 2022  |  Volume : 70  |  Issue : 4  |  Page : 1468--1474

Intraventricular Pilocytic Astrocytoma: A Single Centre Experience

Chinmaya Dash1, Skanda Moorthy1, Kanwaljeet Garg1, Dattaraj Sawarkar1, Pankaj K Singh1, Kavneet Kaur2, Vaishali Suri3, Amandeep Kumar1, Hitesh Gurjar1, Sachin Borkar1, P Sarat Chandra1, Sasank Sarad Kale1,  
1 Department of Neurosurgery, AIIMS, New Delhi, India
2 Department of Pathology, AIIMS, New Delhi, India
3 Department of NeuroPathology, AIIMS, New Delhi, India

Correspondence Address:
Pankaj K Singh
Department of Neurosurgery, AIIMS, New Delhi - 110 029
India

Abstract

Background : Intraventricular pilocytic astrocytomas are a rare occurrence, accounting for approximately 4% -15.6% of all pilocytic astrocytomas .The aim of the study was to describe the radiology, surgical management and outcome in 15 patients with histopathologically proven intraventricular pilocytic astrocytoma(IVPA). Objective : To study the clinical presentation radiology and operative challenges in rare intra ventricular pilocytic astrocytomas. Materials and Methods: Between January 2010 and August 2018, 15 patients with histopathologically proven IVPA were identified. The radiological images were obtained from PACS. Patient and surgical details were obtained from the computerized discharge summary, OT records and operative notes, whereas follow up was obtained from the record section. Results: Headache with progressive loss of vision was the most common presentation. Duration of symptoms varied from 4 months to 2 years (mean 9. 88 months). Except one patient, all patients with preoperative CT scan revealed calcifications in the lesion, with extensive calcification in 3 patients. All the tumors were predominantly hypointense on T1WI and iso to hyperintense on T2WI. Lesion in all patients showed heterogenous contrast enhancement on post gadolinium images. Mean blood loss in the series was 1969 ml (range 250 ml- 4500 ml).There was one death in this series due to meningitis and septic shock. Conclusion: IVPAs are rare tumors and are difficult to diagnose in the preoperative period based on the radiologic profile alone. These tumors can be extremely vascular with potential for massive blood loss. These tumors can be associated with extensive calcification and the calcified tumors have less bleeding as expected.



How to cite this article:
Dash C, Moorthy S, Garg K, Sawarkar D, Singh PK, Kaur K, Suri V, Kumar A, Gurjar H, Borkar S, Chandra P S, Kale SS. Intraventricular Pilocytic Astrocytoma: A Single Centre Experience.Neurol India 2022;70:1468-1474


How to cite this URL:
Dash C, Moorthy S, Garg K, Sawarkar D, Singh PK, Kaur K, Suri V, Kumar A, Gurjar H, Borkar S, Chandra P S, Kale SS. Intraventricular Pilocytic Astrocytoma: A Single Centre Experience. Neurol India [serial online] 2022 [cited 2022 Nov 28 ];70:1468-1474
Available from: https://www.neurologyindia.com/text.asp?2022/70/4/1468/355185


Full Text



Intraventricular tumors are a rare group of intracranial tumors accounting for less than 10% of the cases.[1] They arise from periventricular structures like, choroid plexus, lining of the ventricles, septum pellucidum, etc. Along with their rarity of occurrence they also pose diagnostic challenge radiologically. The differential diagnosis for intraventricular tumors include choroid plexus tumors (papilloma, carcinoma), central neurocytoma, subependymal giant cell astrocytoma, meningioma, ependymoma etc.[2] Pilocytic astrocytoma is a slow-growing tumor which has been classified as grade I astrocytomas according to the World Health Organisation's 2016 classification of central nervous system (CNS) tumors.[3] They account for approximately 2.3% of all CNS tumors. The incidence is higher in pediatric population ranging from 8-23.5% of pediatric CNS tumors.[4] Cerebellum is the most common site of occurrence,[5] the other sites being visual pathway, hypothalamus, diencephalon, and brain stem. Intraventricular pilocytic astrocytomas (IV PA) are very rare and account for about 4% of all the pilocytic tumors.[6] There are only few cases of IV PA described in the literature. We present a series of 15 patients of intraventricular pilocytic astrocytoma. We intend to describe the radiology, surgical management, and outcome in these patients.

 Materials and Methods



Histopathological records of all patients operated for intraventricular tumors between January 2010 and August 2018 were searched and patients with histopathologically proven intraventricular pilocytic astrocytoma were included in the study. Patients across all age groups were included in the study. Patients who had surgery outside our hospital or were re-operated were excluded from the study. Patients with tumors in the cerebellum with extension into the fourth ventricle, are relatively straight forward in their diagnosis based on imaging[2],[7],[8] and hence were excluded from the study. The study is aimed at describing the radiological features, intraoperative events and complications and follow-up in patients with intraventricular pilocytic astrocytoma, as this is a rare entity and not much has been reported in literature regarding this entity. The radiological images were obtained from picture archiving and communication system (PACS). Patient and surgical details were obtained from the computerized database of our hospital. We noted their clinical presentation, radiological findings, different operative approaches used, intraoperative findings blood loss, complications.

 Results



Between January 2010 and August 2018, 15 patients with intraventricular tumors (9 male and 6 female patients) were found to have pilocytic astrocytoma on histopathological examination and were included in our study. Their demographic, clinical, radiological, operative details, complications and follow-up have been summarized in [Table 1]. Duration of symptoms varied from 4 months to 2 years (mean 9.88 months). Headache with progressive loss of vision was the most common presentation. The probable reason was because of raised intracranial pressure and the delay in referral to our center from the peripheral centers. Nine out of 15 patients were younger than 18 years of age with mean age being 23.4 years and median 18 years. Seven patients had the tumor in right lateral ventricle, 5 patients in left lateral ventricle, 2 patients had in third ventricle and 1 patient had the tumor in bilateral lateral ventricles.{Table 1}

One patient was operated only with a preoperative MRI whereas the rest 14 patients had both CT and MRI scans. Except one patient, all patients with preoperative CT scan revealed calcifications in the lesion, with extensive calcification in three patients. All the tumors had mixed intensity on T1 and T2 weighted imaging (WI) with lesion predominantly being hypointense on T1WI and iso to hyperintense on T2WI. Lesion in all patients showed heterogenous contrast enhancement on postgadolinium images. Two patients in whom Diffusion-Weighted imaging (DWI) was available showed restricted diffusion. Two patients underwent surgery via the transcallosal approach whereas the rest of the patients underwent surgery via the transcortical trans ventricular approach. Tumors with extensive calcification had lesser amount of intraoperative bleeding. The tumors were extremely vascular with the mean blood loss in the series being 1969 ml (range 250 ml-4500 ml). There was one death in this series due to meningitis and septic shock. Four patients had coagulopathy in the postoperative period as a result of excessive blood loss. Preoperative diagnosis of IVPA could not be made on the basis of clinical and radiologic profile in any case.

Illustrative case 1

A 18-year-old male presented to our center with complaints of headache and progressive diminution of vision for a duration of 9 months. On examination patient had no perception of light (PL negative) in both eyes with bilateral secondary optic–optic atrophy on fundus evaluation. There was no other deficits. [Figure 1] and [Figure 2] describe the preoperative radiologic findings with operative findings, histopathological findings and the postoperative and follow up radiologic findings respectively. Patient has residual weakness on the right side (power 4/5) and is planned for cranioplasty.{Figure 1}{Figure 2}

Illustrative case 2

A 17-year-old girl presented to our center with complaints of headache for 2 years and progressive diminution of vision for 2 months. On examination patient was PL negative in both eyes with bilateral optic atrophy on fundus evaluation. Patient underwent right temporal craniotomy and excision of the tumor via transcortical transventricular approach through the middle temporal gyrus. [Figure 3] describes the preoperative radiology and the postoperative scan. At 2 weeks follow up patient had no fresh deficits.{Figure 3}

 Discussion



Intraventricular pilocytic astrocytomas are of rare occurrence,[9] accounting for approximately 4-15.6% of all pilocytic astrocytomas.[6] The site of origin of IVPA is still not clear. Some authors believe that pilocytic astrocytomas arise from the brain tissue around the ventricles and grow into the ventricles as the ventricle is composed of ependymal and choroid plexus cells and lack astrocyte lineage of cells.[10] We believe that although this could be one of the mechanism of origin of IVPA, choroid plexus cell differentiation into astrocytes could well be another possible explanation for the origin of such tumors based on the radiology and intraoperative findings in our series. Kitada et al. demonstrated that harvested and cultured choroid plexus ependymal cells from mice differentiated into astrocytes after grafting into pre-lesioned spinal cord in mice.[11] Itokazu et al. demonstrated that neuronal progenitor cells exist in the choroid plexus epithelial cells of mice.[12]

Recently Prasongchean et al.[13] while evaluating for the presence of stem/progenitor cell-like properties in choroid plexus of chicks concluded that neurogenesis can occur from neural precursors within the developing choroid plexus. However, this hypothesis should be taken with a pinch of salt as there is no such human study till date to confirm this theory and possible mechanism of origin of such tumors.

Usual age of presentation of PA is in the pediatric and adolescent age groups with the incidence decreasing with advancing age and it is extremely uncommon to find pilocytic astrocytomas in patients >50 years of age.[14] In our study, the age group varied from 10 to 57 years with the mean age in the series being 23 years with nine patients in the age group of 10-20 years. There was slight male predominance with the male to female ratio of 3:2. This is in concordance with the existing literature.[15] The presentation depends on the location, size and the presence of hydrocephalus.[7] In our series the duration of symptoms varied from 4 months to 2 years with a mean of 9.88 months. Headache with diminution of vision was the most common presentation.

Xia et al.[16] in their series of 12 patients concluded that radiologic feature of IVPAs was similar to that of extra ventricular PAs with an enhancing nodule with cysts. They found IVPAs to be hypointense on T1WI and hyperintense on T2WI with heterogeneous enhancement on post-gadolinium images. In our series most of the patients had mixed intensity on T1WI and T2WI with lesions being predominantly hypointense on T1WI and iso to hyperintense on T2WI. In our series, three patients with IVPAs had extensive calcification with 2 more patients having dispersed foci of calcification within the tumor, two patients had tumors mimicking high-grade neoplastic lesion like glioma or ependymoma. None of our patients a diagnosis of pilocytic astrocytoma was made based upon the preoperative radiology. Cyst wall enhancement was seen in two of our patients. The exact cause for enhancement of the cyst wall is not yet known, with some authors considering to be because of active tumor in the cyst wall. However, Beni-Adani et al. found no evidence of tumor cells in the enhancing cyst wall and there was no tumor recurrence 4 years after surgery.[17]

One of the most common differential diagnosis is subependymal giant cell astrocytoma (SEGA) and warrants a short discussion. SEGA occurs almost exclusively in patients with tuberous sclerosis (TS) and occurs in 5 to 10% of patients with TS. They usually occur in the second decade of life and are believed to be arising from subcortical tubers. They have a propensity to arise near the foramen of monro and can be associated with life-threatening hydrocephalus. They are usually isodense to hypodense on CT scan and may be associated with calcification and hemorrhage. They are heterogeneous on T1WI and T2WI[18]. SEGA are considered less vascular tumors although there are rare reports of profuse intraoperative bleeding while operating SEGA.[19] None of the patients in this series had any features suggestive of TS. The radiologic features of various intraventricular tumors as per the existing literature[2],[8] have been summarized in [Table 2].{Table 2}

Barring two cases, all tumors were very vascular with blood loss >1000 ml (range 250 ml-4500 ml; mean blood loss 1969 ml). In two cases hemostasis could not be achieved and mass closure was done after placing intraventricular drain and bone flap was not replaced. Both patients had post-operative DIC and hemiplegia. In both the patients power did improve in the postoperative follow-up. One patient died on postoperative day (POD) 14 due to meningitis and sepsis. Considering the hypervascular nature of such tumors, especially those tumors without significant calcification, option of pre-operative embolization can be done in such patients to reduce intraoperative bleeding if a diagnosis of a benign tumor like PA can be made. Tumor embolization although has its own complications like tumor bleed and neurological deterioration, but is an established method to reduce vascularity of tumors deemed hypervascular on radiology.[20] Our paper provides contribution to the scant literature available on the radiology of such tumors, apart from highlighting the possibility of profuse intraoperative bleeding of such tumors. This can help us in planning surgeries for such tumors.

 Conclusion



ivPAs are rare tumors and are difficult to diagnose in the preoperative period based on the radiologic profile alone. These tumors can be extremely vascular with potential for massive blood loss, with the exception of heavily calcified tumor, in which bleeding may be less. Preoperative radiological diagnosis of pilocytic astrocytoma must be kept as a differential for intraventricular tumors and surgical team should have an anticipation of massive blood loss in these tumors, while making necessary arrangements for tackling profuse intraoperative bleeding.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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