Astrocitoma pilocítico. Formas de presentación

Abstract

Our purpose is to illustrate and describe the typical and atypical imaging findings of supra and infratentorial pilocytic astrocytoma (PA) with computed tomography (CT) and magnetic resonance imaging (MRI). For this, 32 patients with PA from our case series were selected. Twenty-four patients had confirmed PA from histologic analysis. The remaining 8 patients presented optic pathway gliomas and PA was the most accurate presumptive diagnosis. All patients, 20 male and 12 female (age range 10 months-65 years), underwent unenhanced and enhanced MRI. Diffusion-weighted images and MR spectroscopy (MRS) were performed in 6 patients, and 6 patients underwent CT.The locations of the PA selected (n = 32) were: optic pathway and hipotalamous-quiasmatic region (n = 17), cerebellum (n = 7), talamous (n = 6) and cerebral hemisphere (n = 2).At MRI most PA appeared as solid-cystic masses, iso to hypointense in T1-weighted images and hyperintense in T2-weighted images and FLAIR, with post-contrast enhancement.Four patients presented atypical characteristics: 1 solid cerebellum PA with calcifications, 1 hypothalamus PA in a child without NF1 with no contrast enhancement and 1 cerebral hemisphere PA in a 65 year old woman.The PA are regarded as grade I tumors in the WHO classification. The optic pathway and the hypothalamic-quiasmatic region, as well as the posterior fossa are the most frequent locations. PA are typically well-circumscribed and solid-cystic lesions with low cellularity and slow growth.