Imaging Features of Pilocytic Astrocytoma in Cerebral Ventricles

Intraventricular Pilocytic Astrocytoma in Adults: A 25-year Single-Center Case Series and Systematic Review of the Literature

BACKGROUND

Pilocytic astrocytomas (PA) are the most common gliomas in children/adolescents but are less common and poorly studied in adults. Here, we describe the clinical presentation, surgical management, and outcomes of surgically treated adult patients with intraventricular (IV) PA and review the literature.

METHODS

Consecutive adult patients treated for IV brain tumors at a tertiary academic center over 25 years (1997-2023) were identified. Clinical data were reviewed retrospectively for adult IV PA patients. A systematic literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

RESULTS

Eight patients with IV PA were included. Median age was 25 years (range, 18-69 years), and 4 (50%) were female. The most common tumor location was the lateral ventricle (5, 63%), followed by the fourth ventricle (3, 37%). Subtotal and near total resection were the most common surgical outcomes (6 patients, 75%), followed by gross total resection in 2 (25%). Progression or recurrence occurred in 3 patients (37%), requiring repeat resection in 2 patients. The 5-year overall survival and progression-free survival were 67% and 40%, respectively. In addition, 42 cases were identified in the literature.

CONCLUSIONS

PAs in adults are rare and an IV location is even more uncommon. The findings demonstrate the challenges in caring for these patients, with overall- and progression-free survival outcomes being poorer than the general adult PA population. Findings support the employment of surgical techniques and approaches that favor gross total resection when possible. Further studies are needed to better characterize this unique presentation.

Imaging of supratentorial intraventricular masses in children: a pictorial review-part 2

PURPOSE

This article is the second in a two-part series aimed at exploring the spectrum of supratentorial intraventricular masses in children. In particular, this part delves into masses originating from cells of the ventricular lining, those within the septum pellucidum, and brain parenchyma cells extending into the ventricles. The aim of this series is to offer a comprehensive understanding of these supratentorial intraventricular masses, encompassing their primary clinical findings and histological definitions.

METHODS

We conducted a review and analysis of relevant epidemiological data, the current genetics/molecular classifications as per the fifth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (WHO CNS5), and imaging findings. Each supratentorial intraventricular mass was individually evaluated, with a detailed discussion on its clinical and histological features.

RESULTS

This article covers a range of supratentorial intraventricular masses observed in children. These include colloid cysts, subependymal giant cell astrocytomas, ependymomas, gangliogliomas, myxoid glioneuronal tumors, central neurocytomas, high-grade gliomas, pilocytic astrocytomas, cavernous malformations, and other embryonal tumors. Each mass type is characterized both clinically and histologically, offering an in-depth review of their individual imaging characteristics.

CONCLUSION

The WHO CNS5 introduces notable changes, emphasizing the vital importance of molecular diagnostics in classifying pediatric central nervous system tumors. These foundational shifts have significant potential to impact management strategies and, as a result, the outcomes of intraventricular masses in children.

Imaging findings of intraventricular pilocytic astrocytoma

OBJECTIVE

The aim of this study is to present the clinical and imaging findings of 16 patients with intraventricular pilocytic astrocytomas (PAs).

METHODS

16 patients with histopathological diagnosis of intraventricular PA between February 2016 and January 2022 were evaluated retrospectively. Imaging and clinical findings of the patients, as well as apparent diffusion coefficient (ADC) measurements were analyzed.

RESULTS

Of 16 patients, 8 (%50) were male and 8 (%50) were female. The mean age of the patients was 20.8 years (2-44 years range). The most common symptoms in the patients were headache and ataxia. The mean long-axis size of lesions was found to be 48.19 ± 21.59 (range, 15-92 mm). 9 out of 16 lesions (56.2%) were located in the fourth ventricle. The majority of the lesions were iso-hypointense in T1W and hyperintense in T2W images. The mean ADC value of PAs was 1.57 × 10-3 ± 0.2 mm2/s, while the mean thalamic ADC and white matter ADC values were found to be 0.78 × 10-3 ± 0.04 and 0.76 × 10-3 ± 0.06 mm2/s, respectively. There was a statistically significant difference between the ADC values obtained from the solid components of the lesions and the thalami/white matter (p < 0.001).

CONCLUSION

PAs often originate from midline structures, however, they can also be located intraventricularly. Although intraventricular PAs are frequently seen in pediatric population, it should be kept in mind that they can also be seen in adults, albeit rarely.

ADVANCES IN KNOWLEDGE

PA should be considered in the differential diagnosis of intraventricular neoplasms in case of high ADC values.

Intraventricular Pilocytic Astrocytoma: A Single Centre Experience

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.

Use of Second Window ICG in spinal cord biopsy of a mildly contrast-enhancing lesion: Technical note and review of the literature

INTRODUCTION

Indocyanine green (ICG) is commonly used to visualize cerebral vasculature, particularly in the management of cerebral aneurysms. There have also been attempts to use ICG for visualization of tumors. Injection of ICG followed by immediate fluorescence microscopy is limited by the short time window for imaging and administration and restricted depth of imaging. Second Window Indocyanine Green (SWIG) addresses these issues by allowing for longer contrast times and the imaging of deeper regions of brain tissue. Biopsy of spinal cord lesions is often difficult for a variety of reasons, including the delicate nature of the tissue and differentiating normal from lesional tissue visually, especially in lesions with heterogeneous enhancement.

METHODS

In this case report, we describe the use of second window ICG to facilitate the visualization of a spinal cord lesion and subsequent biopsy of the lesion.

RESULTS

This patient is a 24-year-old female who had recurrence of a suprasellar germinoma. An MRI of the rest of the neuraxis was performed to assess for the presence of drop metastases. The spinal cord from C2-5 was expanded with areas of patchy enhancement; however, this lesion was asymptomatic. The patient's oncologist requested a biopsy of this lesion to help direct subsequent care of her recurrent germinoma. The day before surgery, the patient had an intravenous injection of ICG dye. She then underwent a C3-5 laminectomy for biopsy of her cervical intramedullary lesion. After opening of the dura, no visible abnormality of the spinal cord could be identified. A Stryker endoscope showed an area of ICG uptake in the cord at approximately the C3-4 level. A midline myelotomy was centered over the ICG demarcated area and several samples were taken for pathology. Final biopsy results determined the lesion to be spinal cord parenchyma with perivascular and intraparenchymal lymphocytes - not consistent with spinal cord tumor or germinoma.

CONCLUSION

Second Window ICG is effective in visualizing otherwise visually unremarkable spinal cord lesions. This technology can facilitate biopsy of these lesions and possibly their surgical resection.

Intraventricular pilocytic astrocytoma in an adult patient

Pilocytic astrocytomas are tumors of the central nervous system mostly during the first two decades of life. Although they are mostly common in the midline structures of children, pilocytic astrocytoma within the ventricular system of an adult is extremely rare. We report a case of a 38-year old woman with obstructive hydrocephalus secondary to a brain tumor within the third ventricle. On histological examination, the tumor exhibited biphasic growth pattern comprising compacted cellular areas with Rosenthal fibers and loose textured microcystic areas with eosinophilic granular bodies. Mitosis or necrosis was not present. Immunohistochemical studies demonstrated glial fibrillary acid protein (GFAP), Olig2, and ATRX positivity as well as NeuN and EMA negativity. Ki67 labeling index was less than 1%. Molecular studies revealed that there are no isocitrate dehydrogenase (IDH) gene mutation and H3F3A mutation. This clinical presentation along with the histologic and molecular findings is consistent with a pilocytic astrocytoma arising in the third ventricle of this adult brain, which indicates that pilocytic astrocytoma can present as an intraventricular tumor in an adult patient and should be routinely included in the differential diagnosis of intraventricular brain neoplasm.

Intraventricular Pilocytic Astrocytoma With KIAA1549/BRAF Fusion Arising in a 44-Year Old

Rare pilocytic astrocytomas (PA) have been described to arise in the ventricles of children. They are even less common in this location for the adult population. We present the case of a 44-year old man presenting with vision and mental status changes. Brain imaging revealed an intraventricular mass within the right ventricular atrium, most consistent with a meningioma. Microscopic examination revealed a neoplasm composed of elongated to plump bipolar astrocytes arranged in a fascicular architecture, accompanied by foci containing numerous Rosenthal fibers. By immunohistochemistry, the tumor cells were positive for vimentin and glial fibrillary acid protein, whereas negative for epithelial membrane antigen. Isocitrate dehydrogenase 1 (R132H) was also negative. By fluorescence in situ hybridization, we detected a KIAA1549/BRAF fusion gene. These findings supported the diagnosis of intraventricular PA arising in an adult.

Multifocal Infratentorial Pilocytic Astrocytoma in an Adult Patient

BACKGROUND

Pilocytic astrocytoma is a benign glial tumor typically presenting in children. It is rare for adults to present with pilocytic astrocytoma and even less likely to manifest with multiple foci of lesions especially in nonoptic or hypothalamic locations.

CASE DESCRIPTION

Our patient was a 37-year old man presenting with varied cranial neuropathies, cerebellar dysfunction, and long tract signs, with imaging demonstrating 3 discrete ill-defined contrast-enhancing lesions affecting the cerebellar peduncles, brainstem, and cervicomedullary junction. Neuronavigation-guided biopsy confirmed World Health Organization grade 1 pilocytic astrocytoma; the patient was treated with radiotherapy.

CONCLUSIONS

To our knowledge, we believe this is the first reported case with multifocal infratentorial pilocytic astrocytoma on presentation in an adult patient in the absence of a prior history of associated risk factors such as neurofibromatosis 1 or chemoradiotherapeutic intervention.

Reliability of Imaging-Based Diagnosis of Lateral Ventricular Masses in Children

OBJECTIVE

We studied the accuracy of the radiologic diagnosis of lateral ventricular masses in children (<20 years of age).

METHODS

In this retrospective study, data were collected from children with lateral ventricular masses managed in our unit between 2001 and 2016. There were 43 patients (26 boys and 17 girls; mean age, 12.1 years; range, 8 months to 20 years). Magnetic resonance imaging was available for 36 patients, whereas in 7 patients only a contrast-enhanced computed tomography scan was available. The images were read independently by 3 radiologists, who were blinded to the pathology. Two differential diagnoses were offered for each patient. The agreement between the 3 radiologists was calculated using the Fleiss κ statistic.

RESULTS

The common pathologic diagnoses were subependymal giant cell astrocytoma (SEGA) (20.9%), low-grade astrocytoma (16.3%), high-grade astrocytoma (9.3%), choroid plexus papilloma (9.3%), and meningioma (9.3%). The sensitivity, specificity, and accuracy of the radiologic diagnoses were 62%, 96.7%, and 94.2%, respectively. Low-grade tumors such as low-grade gliomas, SEGAs, choroid plexus papillomas, and meningiomas were diagnosed with a high level of accuracy. High-grade gliomas, choroid plexus carcinomas, and other malignant neoplasms were difficult to diagnose on imaging. Cavernous angiomas were also difficult to diagnose. There was only fair agreement between the 3 radiologists (Fleiss κ = 0.24).

CONCLUSIONS

The pathologic spectrum of lateral ventricular tumors in children is wide, and identifying the pathology on imaging is difficult for malignant tumors. Benign tumors such as SEGAs, low-grade astrocytomas, and choroid plexus papillomas are relatively easier to diagnose. There is significant interobserver variability in the radiologic diagnosis of these tumors.

MR imaging features of spinal pilocytic astrocytoma

Background

The purpose of this retrospective review is to determine the MR imaging features of pilocytic astrocytoma (PA) in the spinal cord to help neuroradiologists preoperatively differentiate PA from other intramedullary tumors.

Methods

Neuro-oncology database review revealed 13 consecutive patients with a pathological spinal PA diagnosis and availability of preoperative MR imaging. Three patients had preoperative diffusion-weighted MR imaging. Demographics and conventional and diffusion MR imaging records were retrospectively evaluated.

Results

Among 13 cases of spinal PA, six PAs were located in the cervical region, 4 in the cervical-thoracic region, and 3 in the thoracic region. The average length of vertebral segments involved for the tumors were 4.7 ± 4.6 segments. Six tumors had associated syringomyelia. Eight PAs were located eccentrically in the spinal cord, and eleven had well-defined margins. Eight tumors (61.5%) were intermixed cystic and solid. All were contrast-enhanced, and 53.8% of all PAs showed focal nodule enhancement of the solid components. Two PAs showed intratumoral hemorrhages, and only one demonstrated cap sign. The ADC values (n = 3) of the tumors were 1.40 ± 0.28 × 10^− 3 mm²/s (min–max: 1.17–1.71 × 10^− 3 mm²/s).

Conclusions

PA should be considered in the differential diagnosis of intramedullary tumors that occur in the cervical and thoracic regions. Eccentric growth pattern, well-defined margin, intermixed cystic and solid appearance, focal nodular enhancement of solid components and syringomyelia are relatively frequent features. Relatively high ADC values compared with normal-appearing spinal cord parenchyma are common in spinal PA.

Simultaneous Supratentorial and Infratentorial Pilocytic Astrocytomas in an Adult Patient with Concurrent Neurofibromatosis Type 1 and HIV Infection

BACKGROUND

Neurofibromatosis type 1 (NF1) has been identified as a predisposing factor in the development of pilocytic astrocytoma (PA), a common benign central nervous system tumor. Although this is a common association, simultaneous development of multiple lesions is an infrequent finding, especially in nonoptic and hypothalamic locations.

CASE DESCRIPTION

A 41-year-old female patient with NF1 and uncontrolled human immunodeficiency virus (HIV) type 1 infection presented with a first generalized seizure and associated headache and ataxia. Imaging studies revealed 2 large intra-axial PAs, nodular-cystic in the supratentorial compartment and solid in the infratentorial compartment. Both lesions were treated by gross total resection in 2 surgeries performed 1 week apart. Despite their different imaging patterns, the tumors were histologically and genetically identical.

CONCLUSIONS

We present a unique case involving 2 histologically and genetically identical PAs occurring simultaneously in supratentorial and infratentorial locations. We suggest that an intrinsic predisposition to tumor development in patients with NF1 might have been enhanced by the HIV-related immunosuppression in this case. Strict oncologic surveillance is essential in patients with a tumor predisposition syndrome combined with immunosuppression.