Craniopharyngiomas account for 80–90% of neoplasms arising in the pituitary region. They originate from squamous rest cells of the remnant of Rathke’s pouch between the adenohypophysis and neurohypophysis in the region of the pars tuberalis. Rathke’s pouch is a cystic diverticulum from the roof of the embryonic mouth that gives rise to the adenohypophysis and determines the induction of the neurohypophysis. This tumor constitutes 3-5% of all intracranial expanding lesions (2), 6% during the pediatric age (3), and shows a bimodal distribution during the first-second decade of life and then in the fifth (4), apparently without any gender difference (5). The tumor generally originates in the suprasellar region (90%), whereas intra- and suprasellar localizations (18%) or solely intrasellar (5%) are less frequent, and extremely rare the forms originating in the III ventricle (2), in the rhinopharynx or in the sphenoid (6,7). The overall incidence of craniopharyngiomas in the United States is 1.3 /10-6 person/ year (8).
Craniopharyngiomas are benign from a histological evaluation but they can be aggressive, invading surrounding bony structures and tissues; they commonly have cystic components that may be multiple and generally cause compression of adjacent neurological structures.
Neurological disturbances, such as headache and visual field defects, together with manifestations of endocrine deficiency such as stunted growth and delayed puberty are the common presenting symptoms of craniopharyngiomas. Stretching of the diaphragm sellae by the enlarging mass is one of the most likely cause of headache, while obstruction of the aqueduct of Sylvius or the foramina of Monro is a rare complication (8). At diagnosis, endocrine dysfunctions are found in up to 80% of patients (9). Reduced GH secretion is the most frequent finding, present in up to 75% of patients, followed by FSH/LH deficiency in 40%, ACTH and TSH deficiency in 25%. Despite the fact that the tumor is frequently large at presentation, the pituitary stalk is usually not disrupted, and hyperprolactinemia secondary to pituitary stalk compression is found in only 20% of patients. Diabetes insipidus is also relatively uncommon, occurring in 8-35% of patients (10,11). The recent availability of high resolution magnetic resonance imaging (MRI) has greatly improved the visualization and radiological diagnosis of craniopharyngiomas. The results of previously published series based on plain skull x-rays have now to be revised. The neuroradiological diagnosis of craniopharyngiomas is based on the features of the lesion itself and on its relations with the surrounding structures. The diagnosis is mainly based on the three characteristic components of the tumor: cystic, solid and calcified (12,13). The cystic component (Fig.1) constitutes the most important tumor part (up to the 70-75% of the total volume), and shows a variable signal depending on the chemical-physical properties of its content (14). A fluid content will appear hypointense in T1 and hyperintense in T2 while a lipid (due to cholesterol), methemoglobin or protein content will appear as hyperintense in T1 and T2 sequences. The solid portion shows an isointense signal in T1 and a hyperintense signal in T2 with an enhancement after gadolinium, at variance with the cystic component (Fig.2). However, the enhancement after paramagnetic contrast is not a consistent feature (14). Calcifications appear as areas of low signal in all sequences; small calcifications can be better visualized at computed tomography (2). The radiological appearance of non-homogeneous signal at prevalent cystic component should not be regarded as a proof of a craniopharyngioma, since macroadenomas can also be characterized by patterns resembling craniopharyngiomas (Fig.3,4).
Figure 1a. Resonance Imaging T1-weighted sequences on coronal planes. Intra- and suprasellar craniopharyngioma in a 8 yr old boy presenting with reduced growth velocity and headache. This tumor has a total cystic component as shown by the hyper-intense spontaneous signal. (Kindly provided by S. Cirillo, II University of Naples).
Figure 1b. Resonance Imaging T1-weighted sequences on sagittal planes. Intra- and suprasellar craniopharyngioma in a 8 yr old boy presenting with reduced growth velocity and headache. This tumor has a total cystic component as shown by the hyper-intense spontaneous signal. (Kindly provided by S. Cirillo, II University of Naples).
Figure 2a. Resonance Imaging T1-weighted sequences on sagittal plan before i.v. gadolinium chelate (diethylene-triamine pentacetate) administration. Extra-axial craniopharyngioma developing into the intra- and suprasellar space, with non-homogenous signal due to calcifications and cysts, in a 7 yr old boy presenting with reduced growth velocity, sleepiness and visual loss. (Kindly provided by S. Cirillo, II University of Naples).
Figure 2b. Resonance Imaging T1-weighted sequences on sagittal plan after i.v. gadolinium chelate (diethylene-triamine pentacetate) administration. Extra-axial craniopharyngioma developing into the intra- and suprasellar space, with non-homogenous signal due to calcifications and cysts, in a 7 yr old boy presenting with reduced growth velocity, sleepiness and visual loss. After contrast medium (B) non-homogenous enhancement of the solid component. (Kindly provided by S. Cirillo, II University of Naples).
Figure 3a. Resonance Imaging T1-weighted sequences on the coronal plane. Intra- and suprasellar PRL-secreting macroadenoma with a prevalent cystic component in a 13 yr old girl presenting with amenorrhea, galactorrhea and reduced visual acuity and field. (Kindly provided by S. Cirillo, II University of Naples).
Figure 3b. Resonance Imaging DPw sequences on the coronal plane. Intra- and suprasellar PRL-secreting macroadenoma with a prevalent cystic component in a 13 yr old girl presenting with amenorrhea, galactorrhea and reduced visual acuity and field. (Kindly provided by S. Cirillo, II University of Naples).
Figure 4a. Resonance Imaging T1-weighted sequences on sagittal plan before gadolinium chelate (diethylene-triamine pentacetate) administration. Extra-axial macroadenoma developing into the intra- and suprasellar and parasellar space including carotid arteries (arrows), with non-homogenous signal due to calcifications and cysts. (Kindly provided by S. Cirillo, II University of Naples).
Figure 4b. Resonance Imaging T1-weighted sequences on sagittal plan after i.v. (B) gadolinium chelate (diethylene-triamine pentacetate) administration. Extra-axial macroadenoma developing into the intra- and suprasellar and parasellar space including carotid arteries (arrows), with non-homogenous signal due to calcifications and cysts. After contrast medium (B) non-homogenous enhancement of the solid and the cystic component (interrupted arrow). (Kindly provided by S. Cirillo, II University of Naples).
The treatment of choice is total tumor resection. In small intrasellar or enclosed tumors, total resection is most easily achieved, and adjunctive radiotherapy is unnecessary. Radiotherapy is required in case of incomplete tumor removal which is common for extra-sellar craniopharyngiomas (the majority of cases). Surgical morbidity depends on tumor size and invasiveness, the experience of the surgeon, and the route of surgical approach. The risk of hypothalamic damage is significantly greater in large invasive tumors treated by trans-cranial approach. Near total excision of the tumor by an experienced pituitary surgeon sparing the hypothalamus, carotids, and visual apparatus, followed by fractionated radiotherapy provides the best hope of low long-term morbidity and longer survival (15-18). Regardless of the approach, the incidence of endocrine dysfunction is high following surgical treatment (15,19), although it is lower after the trans-sphenoidal approach (17). Post-operative diabetes insipidus is reported in 70-90% after surgery (11). Obesity is also frequently found postoperatively: 25 of 43 children with craniopharyngioma became obese after surgery particularly if BMI SDS at presentation was higher and hydrocephalus was present pre-operatively (20). Observations indicate that reduced physical activity and increased daytime sleepiness might also be risk factors for obesity. (21)
Localized intracavity Yttrium, 32P, and other radioactive implants, given as additional treatment, have proven useful for recurrent tumors with a predominant cystic component (8). Hyperfractionated multiportal stereotactic radiotherapy and γ-knife radiosurgery are promising future therapeutic alternatives to standard radiotherapy, due to their potential ability to reduce treatment-associated morbidity in this condition. In children, however, the benefit of any additional radiotherapic treatment should be balanced against the high risk of inducing hypopituitarism later in life. In a retrospective preliminary review aiming at evaluating the efficacy and toxicity of fractionated proton radiotherapy in the management of pediatric craniopharyngioma local mass control was reported in 14 of 15 patients with few acute side effects and newly diagnosed panhypopituitarism, cerebrovascular accident (from which the patient recovered), and an out-of-proton-field meningioma in a single patient who received previous radiotherapy as long-term complications (22).
However, attention should be paid toward late effects arising after treatment of pediatric craniopharyngioma, including decreased postoperative physical health and behavioral functioning (23).