Pilocytic Astrocytoma: Pathological and Immunohistochemical Factors Affecting Surgical Treatment and Surveillance

Abstract

Tumors of the central nervous system are the most prevalent solid neoplasm in the pediatric population and represent a considerable burden to children, physicians, and the healthcare system. High-grade tumors frequently require surgical resection, followed by aggressive adjuvant therapy. Low-grade lesions, in contrast, are often controlled with surgical resection alone, though adjuvant treatment modalities may be necessary if the location of the tumor prevents complete surgical removal. Pilocytic astrocytomas (PAs) are low-grade central nervous system neoplasms that typically affect children. Many PAs are cured with resection alone; others frequently recur despite aggressive management. The ability to distinguish these two groups would be valuable for the treating clinician. Age and extent of resection have long been recognized as two important prognostic variables concerning low-grade, pediatric gliomas (Garcia et al. (J Neurosurg 71:661–664, 1989); Pollack et al. (J Neurosurg 82:536–547, 1995); Gajjar et al. (J Clin Oncol 15:2792–2799, 1997); Fisher et al. (Pediatr Blood Cancer 51:245–250, 2008)). However, additional prognostic markers are necessary in the ongoing effort to correctly identify tumors at particular risk for recurrence or progression. Radiographic characteristics do not adequately predict tumor behavior. Therefore, increasing efforts have been directed toward tumor histology and immunohistochemistry in order to uncover features predictive of aggressive clinical behavior.