597

Juraj Šteno

Craniopharyngiomas and Suprasellar Tumors

CHAPTER

39

l Craniopharyngiomaswithdifferentpointsoforiginoftumorgrowthhavesubstantiallydifferenttopographicalrelationshipswithsurroundingstructuresdeterminingtheirsurgicalresectabilityandtheoutcomeoftreatment;originallyinfradiaphragmatictumorsarethemostamenableforsaferadicalremoval,whichisthebesttreatmentofcraniopharyngiomas.

l Themajorityofcraniopharyngiomasgrowinginsideandoutsidethecavityofthethirdventriclehavestartedtogrowasintrapialtumors,thusacquiringdirectandintimatecon-tactwithhypothalamicstructures.

l Ifthefloorofthethirdventriclecannotbeseendirectlyonpreoperativemagneticresonanceimaging(MRI)

scans,thetopographicalrelationshipofthetumorwithhypothalamicstructuresmaybepredictedaccordingtoitsrelationwiththechiasmandthepresenceorabsenceofhydrocephalus.

l Thenatureandintensityofthetumoradherencetosur-roundingstructuresvaryindifferentcaseswithineachtopographicalgroup.Decisionsabouttheoptimalextentoftumorremovalmaythusbemadeonlyatsurgery.

l Thenaturalhistoryofcraniopharyngiomasisunpredictable,thegrowthpotentialofthetumororitsresidualtumormaydiffersignificantly,andthereforeradiotherapyshouldbeindicatedincaseoftumorprogression.

CLINICAL PEARLS

The region above the sella contains anatomical structures of the hypothalamus-pituitary system (hypothalamic structures and infundibulum with its pars compacta named also the pituitary stalk), the structures of the visual pathways (optic chiasm and adjacent portions of the optic nerves and the optic tracts), and important blood vessels. The tumors affecting the suprasellar region may belong to (a) tumors of dysembryogenetic origin (craniopharyngioma, epidermoid cyst, dermoid cyst, hamar-toma, germ cell tumors, Rathke’s cleft cyst), (b) tumors orig-inating from the tissues of suprasellar structures (gliomas of the visual pathways and hypothalamus, pituicytoma, granular cell tumor of the neurohypophysis, meningioma), (c) tumors extending into the suprasellar space secondarily, most often from the cavity of the sella (pituitary adenoma, Rathke’s cleft cyst, and other cysts), and (d) systemic tumors affecting the cen-tral nervous system (CNS metastasis, lymphoma, leukemia).1-3

The most common tumors of the region are craniopha-ryngiomas and chiasmatic/hypothalamic gliomas. Differential diagnosis has to be made first of all between the craniopha-ryngiomas and other cystic tumors and between chiasmatic/hypothalamic gliomas and other solid lesions. The majority of these tumors are presented in this chapter.

The structures of optic pathways and the hypothalamus-pituitary system may be involved also by suprasellar menin-giomas or large and giant pituitary adenomas. The latter may

severely displace the floor of the third ventricle upward and may also lead to atrophy of the pia and invade the hypo-thalamus.4 Suprasellar meningiomas originating from the lower leaf of the diaphragm can mimic nonfunctioning pitu-itary adenomas.5 Extremely rare is a meningioma originating from the pituitary stalk having no connection to surrounding dura.6

CRANIOPHARYNGIOMASCraniopharyngiomas, benign extra-axial epithelial tumors, often follow an aggressive clinical course resulting in signifi-cant morbidity and shortened life expectancy. Incomplete tumor removal is followed by progression of the remnants in virtually all patients. Damage to the structures of utmost functional importance due to repeated tumor recurrences and subsequent therapeutic procedures substantially deteriorates the patient’s condition. The most logical treatment seems to be a total tumor removal and thus cure of the patient.

The intention to remove the craniopharyngioma totally whenever technically possible emerged in the past in conjunc-tion with therapeutic and diagnostic improvements: steroid hormone replacement, microsurgery, magnetic resonance imag-ing.7-16 Another attitude to management of craniopharyngiomas,