Discussion
    A pilocytic astrocytoma is the most common pediatric central nervous system glial neoplasm, and the most common pediatric cerebellar neoplasm. Pilocytic astrocytomas usually present within the fi rst two decades of life. The cerebellum, optic nerve, optic chiasm, and hypothalamic regions are the favored locations for the tumor, however it can also be found within the cerebral hemispheres, ventricles, and spinal cord. When the lesion is reported in a cerebral hemisphere, the temporal lobe is the most common site. The nature and duration of the patient’s symptoms is related to the specific location of the tumor category.

Figure 2 (above) Neuronavigation image: nodule in
green and cyst in yellow 

    Classical imaging features include a mixed cystic and solid mass with avid enhancement of the solid component of the mass. This appearance is seen in two-thirds of cases. A mass with enhancement of the cyst wall in conjunction with the mural nodule, necrosis with non-enhancing portion of the mass, and a predominantly solid mass without a cystlike component, are the less common imaging features of this neoplasm. Peri-tumoral edema is rarely noted. Surgical resection is the treatment of choice for this neoplasm with up to 79 % twenty-year survival. Radiation and chemotherapy is reserved for recurrent tumors, and tumors situated within the optic chiasm and hypothalamus.

References Koeller KK & Rushing EJ. From the Archives of the AFIP: Pilocytic Astrocytoma: Radiologic-Pathologic Correlation. RadioGraphics 2004; 24: 1693-1708

The differential diagnosis for the neoplasm presented in this case included a pleomorphic xanthoastrocytoma. The patient underwent a right parietal craniotomy with complete resection of the tumor without complications.