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Neuroradiology Case of the Week

Case 63

Karin Westesson and P-L Westesson MD, PhD, DDS

Clinical Presentation: A 6-year-old boy presented with headache and vomiting. A MRI of the head was requested for evaluation.

Radiological Findings:  There was a suprasellar mass with both cystic and solid components expanding the suprasellar cistern. There was no evidence suggesting that it extended into the sella and compressed the anterior aspect of the third ventricle. Consequently, there was no suggestion that there was hydrocephalus and dilation of the lateral ventricles and transependymal transudation.

Diagnosis: Adamantinomatous craniopharyngioma

Discussion: A craniopharyngioma is an epithelially derived hormonally inactive lesion that arises from squamous epithelia rests along the involuted hypophyseal from the remnants of Rathke’s duct [4,2]. Craniopharyngioma are lobulated, well-delineated cystic masses generally located in the sella turcica, suprasellar cistern and the third ventricle [1,2], but can be anywhere along the craniopharyngeal duct [3]. They vary in size from a few millimeters to several centimeters, but the epicenter is the suprasellar cistern. Three to five percent of intracranial brain tumors are craniopharyngioma and account for six to nine percent of intracranial tumors in the 8 to 12 year old age group. There is also a type of craniopharyngioma that affects adults ages 40 to 60 called a papillary craniopharyngioma, but it is much less common [1].
    Symptoms of a craniopharyngioma are related to the increase in intracranial pressure due to the tumor. They include headache, nausea, vomiting, hormonal imbalances, and visual disturbance [1]. Most hormone imbalances (75%) are lack of growth hormone. Forty percent of patients show a discrepancy of luteinizing hormone. Twenty-five percent of patients show a corticotrophin or thyroid stimulating hormone deficiency. This is important to diagnose because these patients require perioperative replacement corticosteroids during surgery. The visual disturbance is related to an impingement of the tumor on the optic pathway at the level of the chiasm or optic tracts [4].
    CT imaging is used to identify a craniopharyngioma and MR imaging is used to determine the location and extent of the tumor [4]. In a CT, an adamantinomatous craniopharyngioma will show the characteristic calcification as hyperdense areas. A papillary craniopharyngioma will not calcify [3]. The cystic regions of the tumor will show as either hypodense or isodense to cerebral spinal fluid depending on the cholesterol content of the cyst [4]. The nodular regions and the rims will enhance after contrast. On MRI, the tumor will appear heterogeneous. It is hypointense on T1-weighted and hyperintense on T2-weighted. The increased signal is due to protein and blood components in cystic solution [2].
    Treatment of craniopharyngioma is controversial. There have been assertive attempts at total resection, with only moderate results. Limited resection, which carefully avoids damage to adjacent structures, followed by radiotherapy has similar cure rates as total resection but less morbidity [3]. For recurrent lesions, surgery is recommended but rather difficult since craniopharyngiomas tend to be well-encapsulated and adherent and possibly invasive into surrounding tissues, such as the hypothalamus (superior), optic chiasm (anterior), pituitary gland (inferior), and elements of the circle of Willis (peripherally) [4]. Surgery also has a higher mortality rate (30%). Lesions removed by surgery often recur within 5 years of the surgery [1].

References:

1. Lum C, Kucharczyk W, Montanera WJ, Becker, LE. Sella turcica and parasellar region. Magnetic Resonance Imaging of the Brain and Spine, 3rd ed. Ed. Scott W. Atlas. Philadelphia: Lippincott Williams and Wilkins, 2002; 1313-1318.
2. Osborn, AG. Diagnostic Neuroradiology. St. Louis: Mosby, 1994.
3. Sanders WP, Chundi VV. Extra-Axial Tumors Including Pituitary and Parasellar. In: Neuroimaging. Ed. William W. Orrison, Jr. Philadelphia: W. B. Saunders Co, 2002; 696-700.
4. Zimmerman RA., Bilaniuk LT, Savino PJ. “Visual pathways.” In: Head and Neck Imaging, 4th ed. Eds. Peter M. Som and Hugh D. Curtain. St. Louis: Mosby, 2003; 751-752.