Radiography
Findings
Digital radiograph in a 23-year-old woman (same patient as in Image 4 in Multimedia) demonstrates characteristic calcifications (arrow) in the suprasellar space. This appearance can easily be misinterpreted as that of an aneurysm.
Digital radiograph in a 39-year-old man (same patient as in Image 8 in Multimedia) demonstrates characteristic expansion of the sella turcica (arrows).
A lateral radiogram of the skull may demonstrate calcifications in either the sella turcica or suprasellar space (see Image above and Image 7 in Multimedia), or it may demonstrate sellar expansion or erosion of clinoid process or dorsum sella (see Image above and Image 10 in Multimedia). These calcifications can be confused with curvilinear calcifications observed with large aneurysms (occasionally referred to as eggshell calcifications). An aneurysm may be differentiated on contrast-enhanced CT, which demonstrates characteristic enhancement of the remainder of the lumen of the aneurysm, and on MRI, which shows heterogeneity of signal intensity and misregistration artifact from turbulent or pulsatile flow in the aneurysm. MRA further helps to elucidate the diagnosis in questionable cases.2,12,13,14,16,21
Degree of Confidence
The degree of confidence for a negative result is low because small calcifications can be missed easily. When observed, calcifications are a nonspecific finding. Soft tissue visualization on plain radiography is poor; therefore, differentiation of the type of tumor present is not possible without further imaging.
False Positives/Negatives
The rate of false-negative results is high because calcified lesions can be missed easily.
Computed Tomography
Findings
Axial CT scan in a 39-year-old man (same patient as in Images 9-10 in Multimedia) obtained without contrast enhancement demonstrates a large, cystic mass (arrow) in the suprasellar space that has predominantly fluid attenuation.
On CT, the adamantinomatous-type tumor appears as a predominately cystic mass (see Image above and Image 8 in Multimedia) with a solid component (>90%). The solid component appears isoattenuating and usually contains calcifications (>80%). The sella may be expansile, and hydrocephalus may be present, depending on the exact location of the tumor (see Anatomy). Tumors of the papillary type are usually solid and isoattenuating; they are rarely calcified. Occasionally, craniopharyngioma may appear as an intraventricular, homogeneous soft tissue mass without calcifications but possibly with hypoattenuating regions; this is observed in the papillary subtype.14
CT scan in a 39-year-old man (same patient as in Image 8 in Multimedia) obtained with intravenous contrast agent shows enhancement of the anterior, solid component (arrows).
The location of the adamantinomatous subtype is characteristic because most are located in the sella or suprasellar region. Contrast enhancement is characteristic of the solid component (see Image above and Image 9 in Multimedia) and cyst wall (90% cases), and an enhanced study may demonstrate displacement of the A1 segment of the anterior cerebral artery (see Image below and Image 12 in Multimedia). Displacement of the optic chiasm also may be observed.
Axial contrast-enhanced CT scan in a 65-year-old man demonstrates a large, calcified suprasellar mass with anterior displacement of the A1 segment of the anterior cerebral arteries (yellow arrows). The anterior communicating artery is not well depicted.
On CT, the cystic component of the tumor extends anteriorly and/or laterally and typically wraps around the solid component. Conversely, the solid component characteristically extends posteriorly and laterally.
Degree of Confidence
The degree of confidence is high because CT is sensitive for calcifications and for visualizing the cystic nature of masses.
False Positives/Negatives
As with MRI, the noncalcified, papillary variant may sometimes be missed.
A Rathke cleft cyst is rarely calcified, whereas more than 90% of craniopharyngiomas are calcified.
Please refer to specific findings in the MRI section below for other differential diagnostic findings.
Magnetic Resonance Imaging
Findings
Contrast-enhanced T1-weighted image demonstrates a complex cystic mass (arrow) in the suprasellar space.
On MRI, the more common adamantinomatous subtype appears as a predominately cystic suprasellar mass with a solid component (see Image above and Image 1 in Multimedia). Characteristic calcifications may not be discernible, though gradient-echo (GRE) images may show susceptibility effects from calcified components. Cystic areas appear hyperintense on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images with heterogeneous isointense to hypointense solid components.12,14,16,18,22,23
Changes in signal intensity vary on T1-weighted images, depending on the cystic contents, which can appear hyperintense if they have a high protein, blood product, and/or cholesterol content in the classic adamantinomatous type. In the papillary variety, solid components appear isointense on T1-weighted images.
Magnetic resonance (MR) spectroscopy shows a prominent lipid spectrum (around 1 ppm) in terms of the cystic contents. Diffusion-weighted images demonstrate variable signal intensity, which reflects the cystic contents.
The sella may be expansile, and hydrocephalus may be present, depending on the exact location of the tumor (see Anatomy). Compression of the third ventricle may occur; when present, such compression helps in distinguishing craniopharyingioma from Rathke's cleft cyst or pituitary adenoma. Occasionally, craniopharyngiomas appear as intraventricular, homogeneous, soft tissue masses without calcifications. They may contain regions of low signal intensity; this is observed in the papillary subtype.
Coronal T1-weighted image in a 65-year-old man (same patient as in Image 12 in Multimedia) obtained through the sella turcica. Image demonstrates a predominantly sellar lesion (arrows) with some suprasellar extension.
Contrast-enhanced T1-weighted image in a 66-year-old woman obtained in a slightly lateral parasagittal plane demonstrates irregular enhancement of the solid components (arrow) and the outer rim of the tumor, which has a predominantly cystic composition.
Sagittal nonenhanced T1-weighted image demonstrates a heterogeneous, cystic mass (arrows) in the suprasellar space (same patient as in Image 14 in Multimedia).
Some craniopharyingiomas can be both intrasellar and suprasellar, having a "snowman" appearance.23 The location of the adamantinomatous subtype is characteristic, with most tumors located in the sellar or suprasellar region (see Images above and Images 13-15 in Multimedia). Contrast enhancement is characteristic (see Images below and Images 2, 6 in Multimedia). MR angiography may demonstrate displacement of the A1 segment of the anterior cerebral artery; displacement of the optic chiasm may also be observed.
Sagittal contrast-enhanced T1-weighted MRI demonstrates a complex cystic, suprasellar mass that is heterogeneously enhancing (arrow).
Gadolinium-enhanced parasagittal T1-weighted MRI in a 23-year-old woman (same patient as in Image 4 in Multimedia) demonstrates the characteristic enhancement of the solid component (arrow) of craniopharyngioma.
On MRI, the cystic component of the tumor extends anteriorly and/or laterally and typically wraps around the solid component (see Images below and Images 4-5 in Multimedia). Conversely, the solid component of the tumor characteristically extends posteriorly and laterally (see Image below and Image 3 in Multimedia).
T1-weighted MRI of a 23-year-old woman (same patient as in Images 5-7 in Multimedia) demonstrates a suprasellar mass with characteristic intermediate- to high-signal material in the cystic material (arrows).
Sagittal T1-weighted MRI in a 23-year-old woman (same patient as in Image 4 in Multimedia) demonstrates the high signal intensity of the cystic material (yellow arrow).
Axial contrast-enhanced T1-weighted MRI demonstrates enhancement of the solid component (arrows) of the lesion.
Adjacent brain parenchyma may show hyperintensity on T2-weighted or FLAIR images, which indicates edema from compression of optic chiasm and/or tracts, gliosis, or tumor invasion. Recurrence in both the local tumor bed and along surgical tracts may the result of implantation of craniopharyngioma tissue. Therefore, post-treatment MRI has been recommended, even in patients whose primary tumor was resected completely.18,23
Degree of Confidence
The degree of confidence is high. Although MRI without a GRE sequence can be insensitive for calcifications, it is sensitive for determining the fluid or soft tissue content of a given area.
False Positives/Negatives
False-positive results may occur as a result of misidentification of a similar lesion in the differential diagnosis.
A Rathke cleft cyst (RCC) can usually be differentiated because it is rarely calcified, whereas 64-92% of craniopharyngiomas are calcified. An RCC is also usually associated with anterior infundibular displacement and does not have a solid component. In addition, it shows contrast enhancement less frequently than other tumors do. Small RCCs may be indistinguishable from the rare intrasellar craniopharyngiomas.
A suprasellar arachnoid cyst has angular margins and is entirely cystic, with no solid component or enhancement.
Hypothalamic or chiasmatic astrocytomas arise at their respective locations and appear solid with areas of necrosis. The pilocytic variety may show cystic changes; however, calcification is less common with this tumor than with others. A moderate degree of enhancement may be seen.
Meningiomas demonstrate the dural tail sign, which is absent with craniopharyngiomas. Meningiomas also have a wide dural base and densely adhere to the dura. A craniopharyngioma can grow to more than 5 cm, but most are smaller. Conversely, a germinoma is almost always large, and its signal intensity and enhancement are homogeneous. A cystic component rarely is observed, and a pineal satellite lesion may be present.
Pituitary adenoma is rare in children; it is mostly intrasellar in the microadenoma variety. Macroadenomas may have suprasellar components with cystic, hemorrhagic, and enhancing areas; findings closely mimic those of a craniopharyngioma. However, calcification is rare.
Teratomas contain mixed solid and cystic components, as do craniopharyngiomas, but teratomas typically contain some fat.
Epidermoids can be distinguished by their characteristic scalloped margins and by the fact that, with epidermoids, there is minimal or no peripheral enhancement. Epidermoids are typically strongly hyperintense on diffusion-weighted images. Dermoids also contain a fatty component.
Ultrasonography
Findings
A few case reports have described the use of ultrasonography with color Doppler imaging in the antenatal diagnosis of fetal craniopharyngiomas. Adult craniopharyngiomas have also been evaluated with the use of color Doppler and ultrasonographic contrast agents.14,16,19
Degree of Confidence
Ultrasonography may be useful for prenatal imaging; however, the modality is operator dependent, it can be limited because of beam attenuation by the bony skull vault, and lesions may be missed.
With the wide availability and documented accuracy of CT and MRI, ultrasonography has not been accepted as a universal tool for the evaluation of pituitary masses.
Nuclear Imaging
Findings
Although evidence of increased metabolic activity in the tumor mass and surrounding brain has been observed, nuclear evaluation is not preferred for the diagnosis of craniopharyngioma.
Angiography
Findings
Angiogram obtained at the same time as Image 12 (see Image 12 in Multimedia) in anteroposterior projection clearly shows elevations of the A1 segment of the anterior cerebral artery (arrows) and anterior communicating artery.
Most of the findings relate to displacement of the cerebral vasculature secondary to mass effect. Specifically, the position of the anterior cerebral artery is well correlated with the location of the tumor. When the A1 segment of the anterior cerebral artery and the anterior communicating artery are in the usual position, the tumor is contained entirely or almost entirely within the sella.
When the A1 segment and the anterior communicating artery are elevated (see Image above and Image 11 in Multimedia) but the basilar artery is in the usual position, the tumor protrudes anteriorly and projects between the optic nerves, deviating the chiasm posteriorly. When the A1 segment and the anterior communicating artery are elevated and the basilar artery is displaced posteriorly, the tumor protrudes posteriorly and pushes the chiasm anteriorly. Stretching of the posterior communicating arteries also may be noted. An unreliable finding is a small, vascular blush in the region of the tumor.
CTA and MRA have supplanted angiography as the primary diagnostic techniques, and angiography is now rarely needed to differentiate the tumor from an aneurysm of the anterior communicating artery.
Degree of Confidence
Angiography findings are nonspecific.
False Positives/Negatives
Other tumors can produce similar angiographic findings.
More on Craniopharyngioma |
| Overview: Craniopharyngioma |
 Imaging: Craniopharyngioma |
| Follow-up: Craniopharyngioma |
| Multimedia: Craniopharyngioma |
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Further Reading
Keywords
Rathke pouch tumor, craniopharyngeal duct tumor, hemangioblastoma, ameloblastoma, adamantinoma, dysodontogenic epithelial tumor, adamantinomatous tumor, papillary tumor, sellar craniopharyngioma, prechiasmatic craniopharyngioma, retrochiasmatic craniopharyngioma
