Craniopharyngioma

Updated by Andrew J. Bishop

BACKGROUND

What is the origin of craniopharyngioma?

Epithelial tumor derived from Rathke’s pouch, the embryonic precursor to the anterior pituitary

In what region of the brain does it usually arise?

Suprasellar region (most common), sella proper (less common)

Are craniopharyngiomas malignant?

No. They are histologically benign but behave aggressively with frequent local recurrences and morbidity due to the location of Dz.

Approximately how many cases of craniopharyngioma occur annually in the U.S.?

~300–350 cases/yr of craniopharyngioma in the U.S., accounting for 1%–3% of all pediatric brain tumors.

At what ages does craniopharyngioma occur?

Commonly occur between ages 5–10 yrs. There is a bimodal distribution (5–15 yrs and 45–60 yrs); one-third of cases occur in pts aged 0–14 yrs.

What are the 2 histologic subtypes of craniopharyngioma?

Adamantinomatous and squamous; thought of as WHO grade 1 tumors

Which subtype is characterized by a solid and cystic pattern?

Adamantinomatous craniopharyngioma has a solid and cystic pattern. A recent study suggests this histology has more frequent LR. (Pekmezci et al., Neurosurgery 2010)

Historically, how has the cyst fluid consistency been described?

“Crankcase (machine) oil”–like (very proteinaceous fluid with cholesterol crystals)

What structures do cysts usually abut superiorly?

Tumors/cysts usually abut the 3^rd ventricle and the hypothalamus superiorly.

Name the most common presenting signs/Sx of craniopharyngioma.

1. HA, n/v (i.e., ↑ ICP)

2. Visual change (bitemporal hemianopsia)

3. Endocrinopathies (TSH, GH, LH/FSH)

What is the most common hormone deficiency at presentation?

At presentation, GH is the most common hormone deficiency.

Do craniopharyngioma tumors respond rapidly or slowly to RT?

Craniopharyngioma tumors respond slowly to RT.

WORKUP/STAGING

What is the workup for a craniopharyngioma?

H&P, basic labs, endocrine/pituitary panel, and MRI of brain

What ancillary studies need to be done before Tx?

Endocrine, audiology, vision, and neuropsychiatric studies

What is the classic appearance of craniopharyngiomas on CT/MRI?

Heterogenous partially calcified nodular suprasellar masses with associated cysts on CT/MRI

Is histology absolutely necessary for the Dx of craniopharyngioma?

No. If necessary, a Dx can be made based on radiographic appearance and cyst fluid analysis.

What is the staging of craniopharyngioma?

There is no formal staging.

TREATMENT/PROGNOSIS

What is the Tx paradigm for craniopharyngioma?

Tx paradigm: max safe resection. Consider EBRT or intracystic chemo adjuvantly or at recurrence

While controversial, what is the favored treatment approach?

STR + RT. The morbidity of a GTR can be detrimental. An STR spares some morbidity and has better QOL (e.g., St. Jude’s data [2002] showed that the surgery group lost an avg of 9.8 IQ points; the more limited surgery + RT group lost an avg of 1.25 points).

What surgical approach is typically employed for craniopharyngioma resection?

Lat pterional approach (temporal craniotomy). Approach depends on location of tumor relative to 3rd ventricle and optic nerves.

What is the rate of GTR?

Large referral centers report GTR rates in 50%–79% of patients.

What % of attempted craniopharyngioma GTRs result in STR?

Depends on location, but overall, 20%–30%. (Tomita T et al., Childs Nerv Syst 2005)

Is observation ever appropriate after incomplete resection for craniopharyngioma?

Yes. Observation is especially appropriate in young pts. Adj and salvage therapy may have similar LC in closely followed pts. However, more surgical procedures often lead to higher morbidity.

What are the RT doses used for craniopharyngioma?

50.4–54 Gy with EBRT in 1.8 Gy/fx, 12–14 Gy with SRS (limited by nearby critical structures)

What volumes are typically irradiated for craniopharyngioma?

GTV is decompressed/postop volume = tumor + cyst wall (cysts decompressed before Tx); PTV is GTV + 0.5–1 cm; no CTV because no microscopic invasion. Be aware of cyst(s) and monitor during RT.

Estimate the 10-yr LC with surgery alone vs. surgery + postop RT for craniopharyngioma.

Surgery (GTR + STR) alone ~42%; surgery + RT ~84% (Stripp DC et al., IJROBP 2004)

Estimate the 10-yr LC with adj RT vs. salvage RT.

Similar rates. Both ~83%–84%. (Stripp DC et al., IJROBP 2004) RT can be deferred for children <5–7 yo after surgery.

In what 3 ways can craniopharyngioma cysts be managed?

Aspiration, radioactive isotope injection, and bleomycin injection, also using intracystic interferon now. (Cavalheiro S et al., Neurosurg Focus 2010)

What isotopes have been used for intracystic RT and what do they deliver?

β-emitting isotopes (yttrium-90, P-32, Rh-186); 200–250 Gy to the cyst wall, be aware of location of chiasm relative to cyst wall.

What is the energy and half-life of P-32 and to what depth is it effective?

0.7 MeV, 2 wks. The effective depth is 3–4 mm.

What are the indications for intralesional cyst management (vs. cyst aspiration)?

Intralesional Tx is an option if the cyst is >50% of total tumor bulk and the number of cysts is ≤3 (ideal if there is a solitary cyst) or for those with recurrent cysts after prior resection

What intracystic chemo has been used?

Bleomycin typically has been used for intralesional cyst management.

What is the typical response rate to intralesional bleomycin?

Limited data, ~65% ORR (29% CR). Median PFS is 1.8 yrs. (Hukin J et al., Cancer 2007)

If a pt has worsening visual Sx while getting adj RT, is this likely due to an acute side effect from RT?

No. Acute Sx during RT are likely due to a rapidly enlarging cystic component; therefore, urgent surgical intervention for decompression is indicated. Radiographic cyst monitoring during RT is recommended to allow for smaller PTV. 15% of cysts increase in size during RT.

Is there a dosimetric advantage to protons vs. photon therapy?

Yes. Compared to IMRT, proton therapy has been shown to reduce dose to the brain and body. (Beltran C et al., IJROBP 2012; Boehling NS, IJROBP 2012) Meaningful clinical differences are uncertain.

What important treatment consideration is needed when treating with protons for craniopharyngioma?

Cyst dynamics. Frequent imaging or resimulations are necessary when treating with protons (or any conformal techniques) to ensure adequate coverage of the cysts (Winkfield KM et al., IJROBP 2009).

What factors have been shown to correlate with inferior LC in craniopharyngioma?

Size >5 cm (Joint Center data: Hetelekidis S et al., IJROBP 1993) and RT dose <55 Gy (Pittsburgh data: Varlotto JM et al., IJROBP 2002)

What is the significance of cyst regrowth after RT?

Cyst regrowth may occur after definitive Tx (does not mean failure, as RT can take a long time to exert its ablative effects). Repeat aspirations are in order if the pt is symptomatic.

What study proposed a risk-stratification scheme to guide the aggressiveness/extent of surgery for craniopharyngioma?

A French study by Puget et al. showed significant reductions in endocrine and hypothalamic dysfunction if pts were stratified prospectively before surgery based on the degree of hypothalamic involvement: grades 0–1, attempt GTR; grade 2, STR (+ RT if >5 yo, observe if <5 yo). (J Neurosurg 2007)

What is the 10-yr OS of pts with craniopharyngioma?

10-yr OS is 70%–92%

What is the long-term survival for pts with craniopharyngioma?

The 20-yr OS is 76%.

TOXICITY

What is the mortality and morbidity rate from surgery for craniopharyngioma?

In modern series, mortality is <4%. Morbidity ranges between 8% and 14%.

What are the most common/serious side effects of surgery?

Diabetes insipidus, hypothalamic obesity, vision loss (<2%), and other hypothalamic injury (defective short-term memory, sleep disturbances)

What are the potential long-term side effects of RT?

Hypopituitarism, cognitive dysfunction or ↓IQ (10%), 2^nd malignancy, and vasculopathy

The hypothalamus should be kept at or below what total RT dose?

If possible, the hypothalamus should not exceed 45 Gy.

How long does it usually take for tumors to regrow? What follow-up is needed?

2 yrs on avg. However, there is a big range, and regrowth can take up to 9 yrs. Thus, the pt requires long-term follow-up with serial MRIs and neuro-ophthalmology or endocrinology exams.

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