Hemorrhagic presentation of frontal partially calcified pilocytic astrocytoma in an 18-year-old woman: A case report and literature review as "clinical case"

We report an unusual case of a frontal partially calcified pilocytic astrocytoma (PA) (WHO grade 1) in an 18-year-old woman who presented with acute, spontaneous intracerebral hemorrhage. Histopathology revealed the PA was mixed with psammoma bodies and areas of vascular proliferation responsible for a hypervascular pattern. The patient underwent a total gross resection. MRI showed no residual tumor at the 18-month follow-up and her neurological deficits improved after rehabilitation. Only 20 cases, including ours, of hemorrhagic presentation of PA in adults have been reported to date with enough radiological data. Furthermore, hemorrhagic presentation of a calcified PA is extremely rare. To date only two other cases of calcified PA with hemorrhagic presentation have been reported, one in an adult and one in an infant as described by Shibao et al. (2012) and Kapoor et al. (2015) respectively. Endothelial proliferation may be the main cause of bleeding in these lesions. In our case, a hypervascular pattern was exhibited by histopathological findings. A diagnosis of PA should be considered, especially when calcifications are present within a hemorrhagic tumor lesion.

Diagnostic accuracy of diffusion weighted imaging for differentiation of supratentorial pilocytic astrocytoma and pleomorphic xanthoastrocytoma

Purpose

Supratentorial pilocytic astrocytoma (PA) may mimic pleomorphic xanthoastrocytoma (PXA) on conventional MR imaging, and a differentiation is clinically important because of distinct recurrence rate and anaplastic transformation rate. The purpose of this study was to investigate the diagnostic potential of diffusion-weighted imaging (DWI) in differentiating supratentorial PA from PXA.

Methods

We retrospectively reviewed DWI and conventional MR imaging of 16 patients with supratentorial PA and 8 patients with PXA. Variables of mean ADC values (ADC_mean) and minimum ADC values (ADC_min) were calculated from the ROIs containing the contrast-enhancing lesion on DWI. ADC_mean values and ADC_min values were compared among all supratentorial PA and PXA as well as between the subgroup of lobar PA and PXA by using an unpaired Student’s t test. The optimum threshold, sensitivity, specificity, accuracy, and the area under the receiver operating characteristic curve (AUC) were determined.

Results

Both ADC_mean values (1542 ± 186 vs 1084 ± 201 × 10⁻⁶ mm²/s; P < 0.001) and ADC_min values (1355 ± 183 vs 988 ± 180 × 10⁻⁶ mm²/s; P < 0.001) were significantly higher in supratentorial PA compared with PXA. The ADC_mean values and ADC_min values were also significantly higher in lobar PA than those in PXA. The ADC_mean values were useful for differentiating supratentorial PA from PXA, with a threshold value of > 1189.8 × 10⁻⁶ mm²/s (sensitivity, 93.8%; specificity, 100%). The optimal threshold values of > 1189.8 × 10⁻⁶ mm²/s for ADC_mean values provide sensitivity and specificity of 85.7 and 100%, respectively, for discriminating lobar PA from PXA. The optimum threshold value for ADC_min was > 1063.5 × 10⁻⁶ mm²/s.

Conclusion

DWI is helpful in characterization and differentiation of supratentorial PA from PXA.

Electronic supplementary material

The online version of this article (10.1007/s00234-018-2036-y) contains supplementary material, which is available to authorized users.