Benign CNS tumors
Craniopharyngioma
A cystic tumor near the vision and hormone centers of the brain, controlled with radiation after partial removal.
Definition
A craniopharyngioma is a benign epithelial tumor arising from remnants of Rathke pouch, sitting in the suprasellar region above the pituitary gland. It has solid and cystic components filled with cholesterol-rich fluid, and even though histologically benign, it is densely adherent to the optic chiasm, hypothalamus, and pituitary stalk. Patients present with visual loss, headaches, endocrine failure, and, in children, growth delay.
How radiation treats it
Radiation arrests growth of both the solid tumor and the cyst wall after limited (subtotal or cyst-aspirated) resection, allowing a strategy that avoids the hypothalamic and visual damage of radical surgical removal. Cyst decompression before radiation shrinks the target, and treatment prevents re-accumulation. Modern conformal and proton therapy have improved cognitive and endocrine outcomes compared with older techniques.
Side effects
- Fatigue and, in children, temporary hair loss over the treatment field.
- Hypothalamic and pituitary dysfunction (diabetes insipidus, obesity, growth and thyroid/adrenal failure) — the dominant long-term toxicity, requiring lifelong endocrine care.
- Visual or cognitive late effects are minimized with conformal planning and proton therapy where available.
Simulation process
CT simulation with a fused thin-slice contrast MRI of the brain and dedicated sella/suprasellar imaging defines the solid component and any residual cyst. The optic chiasm, hypothalamus, brainstem, temporal lobes, and cochleae are contoured as organs at risk. Children are immobilized in a custom mask, sometimes with sedation for daily setup. Because cysts can expand during treatment, a mid-course MRI is commonly repeated to confirm target stability.
Treatment process
Standard treatment is 52.2–54 Gy in 1.8 Gy daily fractions over six weeks, given after maximal safe decompression or partial resection. Proton therapy is preferred at many US pediatric centers to reduce integral brain dose. During the six-week course, patients are monitored for cyst regrowth, and re-imaging mid-treatment allows re-planning if the cyst enlarges. Long-term control is excellent (over 85–90%), with follow-up emphasizing endocrine testing, vision, and neurocognitive development.
Key takeaways for students
- Limited surgery plus radiation beats radical resection for quality of life.
- Re-image mid-treatment — these cysts can grow during the course.
- Hypothalamic-sparing planning and proton therapy are priorities, especially in children.