Diagnosis
Usually – depending on the interview of the patient and after a clinical exam which includes a neurological exam and an ophthalmological exam – a CT scan and/or an MRI scan will be performed to confirm the presence of a tumor. They are usually easily distinguishable from normal brain structures using these imaging techniques. A special dye may be injected into a vein before these scans to provide contrast and make tumors easier to identify. Pilocytic astrocytomas are typically clearly visible on such scans, but it is often difficult to say based on imaging alone what type of tumor is present. If a tumor is found, it will be necessary for a neurosurgeon to perform a biopsy of it. This involves the removal of a small amount of tumorous tissue, which is then sent to a (neuro)pathologist for examination and staging. The biopsy may take place before surgical removal of the tumor, or the sample may be taken during surgery to remove the bulk of the tumor. Microscopic appearance
Pilocytic astrocytomas are often cystic tumors, and, if solid, tend to be well-circumscribed. Under the microscope, the tumor is seen to be composed of bipolar cells with long "hair-like" GFAP-positive processes, giving the designation "pilocytic" (that is, made up of cells that look like fibers when viewed under a microscope). Some pilocytic astrocytomas may be more fibrillary and dense in composition. The presence of Rosenthal fibers, eosinophilic granular bodies, and microcysts can often be seen.
Myxoid foci and oligodendroglioma-like cells may also be present, though these are not specific to pilocytic astrocytoma. Long-standing lesions may show hemosiderin-laden macrophages and calcifications. Treatment
The most common form of treatment is having the tumor surgically removed. Complete removal of the tumor will generally allow functional survival for many years. In particular for pilocytic astrocytomas (commonly indolent masses that may permit normal neurologic function), surgeons may decide to monitor the neoplasms evolution and postpone surgical intervention for some time. However, total resection is often not possible. The location could prohibit access to the neoplasm and lead to incomplete or no resection at all. Left unattended, these tumors may eventually lead to further symptoms due to continued slow growth. Extremely rarely, they may also undergo malignant transformation. If surgery is not possible, recommendations such as chemotherapy or radiation may be suggested. However, side effects from these treatments can be extensive and long term, resulting in some cases in life-long difficulties. Side effects
After treatment, children with pilocytic astrocytoma may experience an improvement of symptoms related to the tumor itself depending on the location, but may also experience side effects related to the treatment:

Symptoms related to increased pressure in the brain often disappear after surgical removal of the tumor. Effects on coordination and balance may improve and might progressively (to completely) disappear as recovery progresses. Steroid treatment is often used to control tissue swelling that may occur pre-and post-operatively. Patients can, however, also develop long-term side effects due to the type of treatment they may receive.