Deadly Proliferation and Transformation of Pilocytic Astrocytoma in Pregnancy

Background: Intracranial tumor growth associated with pregnancy is not an uncommon phenomenon. Pilocytic astrocytoma is typically considered to be an indolent tumor with little to no risk of progression to higher-grade lesion. We present a rare case of cerebellar pilocytic astrocytoma transformation to hemorrhagic high-grade glioma during pregnancy.

Case description: Patient EK was a 32-year-old female with neurofibromatosis type 1 and known cerebellar pilocytic astrocytoma. For nearly a decade before her pregnancy, her cerebellar tumor was stable on imaging. Routine magnetic resonance imaging (MRI) of the head obtained at 20 weeks' gestation continued to demonstrate tumor stability. At 24 weeks' gestation, the patient had sudden, severe headaches. MRI of the head showed evidence of significant tumor expansion. The following day, the patient was found unresponsive. Computed tomography of the head demonstrated hemorrhage within the tumor and tonsillar herniation. Her neurologic examination revealed no brainstem reflexes; however, given her age and pregnancy, she underwent emergent decompression and tumor debulking. Unfortunately, she never improved neurologically. Final pathology identified the lesion as high-grade glioma with anaplastic changes and hemorrhagic conversion.

Conclusions: This is a unique case of indolent cerebellar pilocytic astrocytoma that transformed to high-grade glioma during pregnancy, proven by tumor growth on MRI and anaplasia on pathology. We hypothesize that increased levels of pregnancy hormones (progesterone, vascular endothelial growth factor, placental growth factor, among others) likely contributed to tumor growth. We recommend that all glial tumors be monitored extremely closely throughout pregnancy, and perhaps one should consider surgical treatment (if possible) before patients become pregnant.