Pilocytic astrocytoma mimicking craniopharyngioma: a case series

Comparison of MRI findings of hypothalamic-optic chiasmatic gliomas and craniopharyngiomas

BACKGROUND

Differential diagnosis of hypothalamic-optic chiasmatic gliomas (HOCGs) and craniopharyngiomas on magnetic resonance imaging (MRI) can be quite challenging.

PURPOSE

To compare the MRI features of HOCGs and cranipharyngiomas.

MATERIAL AND METHODS

Patients diagnosed with HOCG or craniopharyngioma in histopathological evaluation between 2012 and 2022 and who underwent preoperative contrast-enhanced brain MRI were included. Various MRI features were retrospectively evaluated for each lesion: T2-weighted imaging and fluid attenuation inversion recovery hyperintensity, calcification, cystic change, T1-weighted (T1W) imaging hyperintensity of the cystic component, hemorrhage, involvement of sellar, suprasellar or other adjacent structures, lobulated appearance, presence of hydrocephalus, and contrast enhancement pattern. Apparent diffusion coefficient (ADC) values were also evaluated and compared.

RESULTS

Among 38 patients included, 13 (34%) had HOCG and 25 (66%) had craniopharyngioma. Craniopharyngiomas had a significantly higher rate of cystic changes, calcification, and T1W imaging hyperintensity of the cystic component than HOCGs (P <0.05). Of HOCGs, 92% had chiasm involvement, 23% had optic nerve involvement, and 31% had brain stem involvement. On the other hand, chiasm involvement was observed in 8% of craniopharyngiomas, but none had optic nerve and/or brain stem involvement (P <0.05). While 62% (8/13) of HOCGs had diffuse homogeneous enhancement, 80% (20/25) of craniopharyngiomas had a diffuse heterogeneous enhancement pattern. Mean ADC values were significantly higher in craniopharyngiomas compared to HOCGs (2.1 vs. 1.6 ×10-3mm2/s, P <0.05).

CONCLUSION

Although some neuroimaging findings may overlap, features such as presence of cyst and calcification, brain stem and optic pathway involvement, different enhancement patterns, and ADC values may be helpful in the differential diagnosis of HOCGs and craniopharyngiomas.

Review of imaging recommendations from Response Assessment in Pediatric Neuro-Oncology (RAPNO)

The Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group includes neuroradiologists, neuro-oncologists, neurosurgeons, radiation oncologists, and clinicians in various additional specialties. This review paper will summarize the imaging recommendations from RAPNO for the six RAPNO publications to date covering pediatric low-grade glioma, pediatric high-grade glioma, medulloblastoma and other leptomeningeal seeding tumors, diffuse intrinsic pontine glioma, ependymoma, and craniopharyngioma.

A novel MRI feature, the cut green pepper sign, can help differentiate a suprasellar pilocytic astrocytoma from an adamantinomatous craniopharyngioma

OBJECTIVE

There are no specific magnetic resonance imaging (MRI) features that distinguish pilocytic astrocytoma (PA) from adamantinomatous craniopharyngioma (ACP). In this study we compared the frequency of a novel enhancement characteristic on MRI (called the cut green pepper sign) in PA and ACP.

METHODS

Consecutive patients with PA (n = 24) and ACP (n = 36) in the suprasellar region were included in the analysis. The cut green pepper sign was evaluated on post-contrast T1WI images independently by 2 neuroradiologists who were unaware of the pathologic diagnosis. The frequency of cut green pepper sign in PA and ACP was compared with Fisher's exact test.

RESULTS

The cut green pepper sign was identified in 50% (12/24) of patients with PA, and 5.6% (2/36) with ACP. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the cut green pepper sign for diagnosing PA were 50%, 94.4%, 85.7% and 73.9%, respectively. There was a statistically significant difference in the age of patients with PA with and without the cut green pepper sign (12.3 ± 9.2 years vs. 5.5 ± 4.4 years, p = 0.035).

CONCLUSION

The novel cut green pepper sign can help distinguish suprasellar PA from ACP on MRI.

Histomorphological spectrum of pediatric supratentorial CNS tumors: A 3-year retrospective study in a tertiary care center

Objective:

Central nervous system (CNS) tumors are the second most common neoplasms in children and they differ from their adult counterparts in terms of incidence, topography, clinical features, histology, and outcome. This article analyzes the incidence of supratentorial tumors, various histopathological entities, and their characteristics in pediatric patients <18 years of age.

Materials and Methods:

This was a retrospective study conducted at the Department of Neuropathology, Institute of Neurosurgery, MMC/RGGGH Chennai from January 2017 to December 2019. Data of supratentorial tumors in children less than 18 years of age procured and their histomorphological profile were analyzed.

Results:

In our institution, of a total of 1134 CNS and spinal neoplasms, 117 pediatric intracranial and 7 spinal neoplasms were reported and the incidence of supratentorial pediatric tumors was 44.44% (52 cases). Among which intraaxial tumors account for 38.46% with 20 cases, extraaxial tumors 51.92% with 27 cases, and intraventricular tumors 9.61% with five reported cases. Most common tumors reported were astrocytomas, craniopharyngioma, followed by ependymoma among others

Conclusion:

Though posterior fossa neoplasms are more common in children, supratentorial tumors show a rising trend worldwide in the pediatric population. Our study gives an overview of the incidence and histopathological profile of supratentorial CNS tumors.

Reappraisal of haemorrhagic suprasellar pilocytic astrocytoma during adulthood

Pilocytic astrocytomas comprise the most common central nervous system tumour during childhood and have an excellent response to surgical treatment in this population. The tumour incidence decreases with age, whereas more aggressive behaviour tends to increase. Haemorrhage as a presenting feature of pilocytic astrocytomas is a rare phenomenon, especially in the adult population. We present a case of a 55-year-old patient with progressive headaches and dizziness. MRI confirmed a sellar and predominantly retrochiasmal suprasellar lesion with heterogeneous signal, enhancement and blood products. Management via transsphenoidal approach was performed, and histopathology revealed the unexpected diagnosis of haemorrhagic pilocytic astrocytoma. Haemorrhagic pilocytic astrocytoma is an infrequent entity in the adult population and it is essential to recognise the peculiarities regarding diagnostic evaluation and management, which differ from the paediatric population. During adulthood, this tumour carries an overall unfavourable prognosis, with higher rates of progression and recurrence.

Supratentorial Pilocytic Astrocytoma Mimicking Convexity Meningioma with Early Anaplastic Transformation: A Case Report

Meningiomas and pilocytic astrocytomas are benign intracranial tumors. Pilocytic astrocytomas arises frequently at the posterior fossa in childhood. Meningiomas have several image findings, such as a dural tail sign, bony erosion, and sunburst appearance on angiography. However, pilocytic astrocytomas with these findings have been rarely reported. In this report, we describe a mass with typical image findings of a meningioma, but diagnosed as a supratentorial pilocytic astrocytoma with early anaplastic transformation.