Craniopharyngioma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Marjan Khan M.B.B.S.[2]
Overview
Craniopharyngiomas are epithelial tumors that usually arise in the pituitary stalk adjacent to the optic chiasm. On gross pathology, craniopharyngiomas are cystic or partially cystic with solid areas.The cyst is filled with a turbid, proteinaceous material of brownish-yellow color that glitters and sparkles because of a high content of floating cholesterol crystals On microscopic histopathology, it is categorized into two subtypes: Adamantinomatous and papillary.
Pathophysiology
- Craniopharyngioma is a nonglial intracranial tumor derived from a malformation of embryonic tissue. [1]
- There are differing hypotheses on its embryonic origin. [1]
- Pathogenesis of craniopharyngioma, although not completely understood. [1]
- Some authorities advocate that it originates from ectodermal remnants of Rathke's pouch. [1]
- Few pathologists believe that it originates from residual embryonal epithelium of the anterior pituitary gland and of the anterior infundibulum. [1]
Embryonic theory
- According to this theory Craniopharyniomas arise from neoplastic transformation of embryonic squamous cell nests of Rathke's pouch with the stomodeum.[2] [1]
- During the process of proliferation and rotation of the cells of Rathke's pouch leading to the formation of the adenohypophysis, cell remnants of the craniopharyngeal duct are spread through the intrasellar and suprasellar region.[2]
- The rotation of the adenohypophysis is caused by different rates of cellular multiplication, resulting in a spread of cells of the craniopharyngeal duct to the suprasellar region.[2]
- The rare location at the cerebellopontine angle could fit with this hypothesis.[2] [1]
Metaplastic theory
- Papillary craniopharyngiomas are the result of metaplasia of the adenohypophyseal cells in the anterior pituitary, resulting in the formation of squamous cell nests.
- This theory is supported by the presence of metaplastic nests in the gland.[2]
Gross Pathology
- On macroscopic examination, craniopharyngiomas are cystic or partially cystic with solid areas. [3] [1]
- Craniopharyngiomas can arise anywhere along the craniopharyngeal canal.
- It occur most often in sellar/suprasellar region but can have anterior extension to the prechiasmatic cistern and subfrontal spaces.[3] [1]
- Posterior extension into the prepontine and interpeduncular cisterns, cerebellopontine angle, third ventricle, posterior fossa, and foramen magnum; and laterally toward the subtemporal spaces.[3]
- Rare locations of craniopharyngiomas are; the nasopharynx , paranasal area , sphenoid bone, ethmoid sinus, intrachiasmatic area, temporal lobe, pineal gland, posterior cranial fossa, cerebellopontine angle, midportion of the midbrain , or completely within the third ventricle.
- Craniopharyngiomas are supplied with blood coming from the anterior circulation: perforators from anterior cerebral artery and the proximal portion of the posterior communicating artery.[4]
- Tumor adhesion is the result of local inflammation. Several inflammatory cytokines have been shown to be elevated in the craniopharyngioma cyst fluid compared with cerbrospinal fluid (CSF).[5] [1]
Microscopic pathology
- The histologic pattern consists of nesting of squamous epithelium bordered by radially arranged cells. It is frequently accompanied by calcium deposition and have a microscopic papillary architecture.[2] [1]
- Two distinct types are recognized:[6][7] [1]
- Adamantinomatous craniopharyngioma
- Papillary craniopharyngioma.
- In the adamantinomatous type, calcifications are visible on neuroimaging and are helpful in diagnosis. [2] [1] [1]
- The papillary type rarely calcifies. On light microscopy, the cysts are seen to be lined by stratified squamous epithelium.
- Keratin pearls may also be seen.
- The cysts are usually filled with a yellow, viscous fluid which is rich in cholesterol crystals.
- Islands of densely packed cells merge with loosely cohesive aggregates of squamous cells known as stellate reticulum.
- Nodules of “wet keratin” representing remnants of pale nuclei embedded within an eosinophilic keratinous mass are found in either the compact or looser areas.
- Cystic cavities containing squamous debris are lined by flattened epithelium.
- Granulomatous inflammation associated with cholesterol clefts and giant cells may be detectable, but this is more typical for xanthogranuloma.
- Piloid gliosis with abundant Rosenthal fibers is often seen at the infiltrative interface of the tumor and should not be mistaken for pilocytic astrocytoma.
- Malignant transformation” of craniopharyngioma appears to be very rare.[2] [1] [1]
- Shown below is a micrograph showing the characteristic features of an adamantinomatous craniopharyngioma - cystic spaces, calcifications, and "wet keratin" pearls on hematoxylin phloxine saffron (HPS) stain.
- Shown below is a Micrograph showing a papillary craniopharyngioma on HPS stain.
Genetics
- Multiple chromosomal abnormalities have been reported by classic cytogenetic analysis.
- Most tumors had abnormalities involving chromosomes 2 and 12.
- More than 70% of adamantinomatous craniopharyngiomas harbor a mutation of the β-catenin gene.
- Most of the mutations affect exon 3, which encodes the degradation targeting box of β-catenin compatible with an accumulation of nuclear β-catenin protein.
- In a few cases of adamantinomatous craniopharyngioma, the same β-catenin mutations occurring in the epithelial cells have been identified in mesenchymal cells.
- No mutations have been demonstrated in papillary craniopharyngioma.
- Comparative genomic hybridization studies on two large series of craniopharyngiomas have failed to show significant chromosomal imbalances in adamantinomatous and papillary craniopharyngioma.
- The mutations of genes encoding β-catenin (CTNNB1 and APC) are an exclusive characteristic of adamantinomatous craniopharyngioma.
- Few researchers demonstrated a causative effect of mutant β-catenin in the etiology of human adamantinomatous craniopharyngioma.
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 Petito CK, DeGirolami U, Earle KM (April 1976). "Craniopharyngiomas: a clinical and pathological review". Cancer. 37 (4): 1944–52. PMID 1260697.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Bunin GR, Surawicz TS, Witman PA, Preston-Martin S, Davis F, Bruner JM (October 1998). "The descriptive epidemiology of craniopharyngioma". J. Neurosurg. 89 (4): 547–51. doi:10.3171/jns.1998.89.4.0547. PMID 9761047.
- ↑ 3.0 3.1 3.2 Weiner HL, Wisoff JH, Rosenberg ME, Kupersmith MJ, Cohen H, Zagzag D, Shiminski-Maher T, Flamm ES, Epstein FJ, Miller DC (December 1994). "Craniopharyngiomas: a clinicopathological analysis of factors predictive of recurrence and functional outcome". Neurosurgery. 35 (6): 1001–10, discussion 1010–1. PMID 7885544.
- ↑ Duff J, Meyer FB, Ilstrup DM, Laws ER, Schleck CD, Scheithauer BW (February 2000). "Long-term outcomes for surgically resected craniopharyngiomas". Neurosurgery. 46 (2): 291–302, discussion 302–5. PMID 10690718.
- ↑ Garrè ML, Cama A (August 2007). "Craniopharyngioma: modern concepts in pathogenesis and treatment". Curr. Opin. Pediatr. 19 (4): 471–9. doi:10.1097/MOP.0b013e3282495a22. PMID 17630614.
- ↑ Sekine S, Shibata T, Kokubu A; et al. (2002). "Craniopharyngiomas of adamantinomatous type harbor beta-catenin gene mutations". Am. J. Pathol. 161 (6): 1997–2001. PMC 1850925. PMID 12466115. Unknown parameter
|month=ignored (help) - ↑ Sekine S, Takata T, Shibata T; et al. (2004). "Expression of enamel proteins and LEF1 in adamantinomatous craniopharyngioma: evidence for its odontogenic epithelial differentiation". Histopathology. 45 (6): 573–9. doi:10.1111/j.1365-2559.2004.02029.x. PMID 15569047. Unknown parameter
|month=ignored (help)