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

Abstract

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.

Keywords: Anaplasia; Astrocytoma; Meningioma; Radiography.

Fig. 1. Preoperative radiographic images. A: T2 weighted MRI showing a mass with multiple cystic portion and peritumoral edema. B: MRI with gadolinium reveals a well-enhancing mass with large dural base on the right frontal convexity area. C: Dura tail signs (black arrows) are identified on MRI with gadolinium. D: Bony thinning on right frontal bone (white arrow) is revealed on computed tomography scans. E: The angiographic image demonstrates sunburst appearance (dotted arrow). F: Sunburst appearance also shows on the lateral image (dotted arrow). MRI, magnetic resonance imaging.

Fig. 2. Intraoperative photography (A) reveals a non-dural based and cystic mass. Photomicrograph of tumor shows Rosenthal fibers (B) and eosinophilic granular bodies (hematoxylin-eosin stain, ×200) (C).

Fig. 3. Postoperative radiographic and pathologic findings. A: No remnant mass is identified on postoperative enhanced CT scans. B: Follow-up CT scans after 9 months shows a mass lesion suspicious of tumor recurrence (white arrow). C: Magnetic resonance imaging with gadolinium reveals a new well-enhancing mass on previous operative site. D: Pathologic findings shows increased cellularity, increased nuclear pleomorphism, and some mitoses (3 mitoses/10 high power field). There was no necrosis. Ki-index was about 30% (hematoxylin-eosin stain, ×200). CT, computed tomography.