Neoplasms in this location may induce hypofunction or hyperfunction of the anterior pituitary, diabetes insipidus, or combinations of these manifestations.
Hypothalamic Suprasellar Tumors
The most commonly implicated lesions of hypothalamic supracellar tumors are _______________
gliomas (sometimes arising in the chiasm; see Chapter 28 ) and craniopharyngiomas.
The_______________ is thought to be derived from vestigial remnants of Rathke pouch. These slow-growing tumors account for 1% to 5% of intracranial tumors; a small minority of these lesions arise within the sella, but most are suprasellar, with or without intrasellar extension.
A bimodal age distribution is observed, with one peak in childhood (5 to 15 years) and a second peak in adults 65 years or older.
Patients usually come to attention because of headaches and visual disturbances, while children might present with growth retardation due to pituitary hypofunction and GH deficiency.
Note: Abnormalities of the WNT signaling pathway, including activating β-catenin mutations, have been reported in craniopharyngiomas.
Craniopharyngiomas average 3 to 4 cm in diameter; they may be encapsulated and solid, but more commonly they are cystic and sometimes multiloculated.
In their strategic location, they often encroach on the optic chiasm or cranial nerves, and not infrequently they bulge into the floor of the third ventricle and base of the brain.
Two distinct histologic variants are recognized: ________________The adamantinomatous type frequently contains radiologically demonstrable calcifications; the papillary variant calcifies only rarely.
- adamantinomatous craniopharyngioma (most often observed in children) and
- papillary craniopharyngioma (most often observed in adults).
" KIDS ARE ADAMANT!!!"
" As you age, your eyes become blurry!!"
________________________ consists of nests or cords of stratified squamous epithelium embedded in a spongy “reticulum” that becomes more prominent in the internal layers.
“Palisading” of the squamous epithelium is frequently observed at the periphery.
What is the diagnostic feature of adamantinomatous craniopharyngioma?
Compact, lamellar keratin formation (“wet keratin”) is a diagnostic feature of this tumor ( Fig. 24-7 ).
As was mentioned above, dystrophic calcification is a frequent finding.
Additional features include cyst formation, fibrosis, and chronic inflammatory reaction.
The cysts of adamantinomatous craniopharyngiomas often contain a cholesterol-rich, thick brownishyellow fluid that has been compared to “machine oil.”
These tumors extend fingerlets of epithelium into adjacent brain, where they elicit a brisk glial reaction.
___________________- contain both solid sheets and papillae lined by welldifferentiated
These tumors usually lack keratin, calcification, and
The squamous cells of the solid sections of the tumor lack the peripheral palisading
and do not typically generate a spongy reticulum in the internal layers.
Patients with craniopharyngiomas, especially those < 5 cm in diameter, have an excellent
recurrencefree and overall survival.
Larger lesions are more invasive but this does not impact
on the prognosis.
Malignant transformation of craniopharyngiomas into squamous carcinomasis exceptionally rare and usually occurs after irradiation.