Fig 1 Suprasellar lesions neoplastic

I, 2. Pituitary macroadenoma. Coronal T1 WI with a pituitary macroadenoma in close relationship with the optic chiasm presenting a heterogeneous, post-contrast high intensity signal.

3. Pituitary macroadenoma. Sagittal T1 WI shows a pituitary tumor with a heterogeneous postcontrast high intensity signal with cystic and/or necrotic features in its posterior section filling the suprasellar cisterns and exerting compression on the optic chiasm.

4, 5. Craniopharyngioma. A suprasellar space-occupying mass with no postcon-

trast enhancement on coronal T1 WI.

6. Meningioma. Sagittal T1 WI shows a suprasellar space-occupying neoplastic lesion with a postcontrast high intensity signal showing an unusual development alongside the pituitary stalk.

7. Optic nerve glioma. Axial T2WI shows a right optic nerve glioma with widening of the optic foramen in a patient with neurofibromatosis type I.

8. 9. Pilocytic astrocytoma. A highly enhanced mass, occupying part of the sella and the suprasellar cisterns and extending behind the optic chiasm, is seen on coronal and sagittal T1 WI respectively. 10. Chordoma. Axial T1 WI demonstrates a multilobular space-occupying neo-plastic lesion, which is heterogeneously and highly enhanced, developing into the left parasellar region and ipsilateral temporal and posterior fossae along the ridge of the petrous bone.

II. Dermoid tumor. Calcification with elements of fat in the retrochiasmatic suprasellar cisterns.

12. Meningioma. Coronal T1 WI shows a postcontrast highly enhancing neo-plastic lesion of the right cavernous sinus.

- Pituitary carcinoma, or carcinosarcoma

- Granular-cell tumor of the pituitary or choristoma

Craniopharyngiomas

Meningiomas

Hypothalamic and optic nerve/chiasm gliomas

Dermoid tumors

These represent 15-20% of primary intracranial tumors, and are the second most frequent suprasellar neoplasm in adults. Rarely, meningiomas may arise from the parasellar lateral wall of the cavernous sinus, and they may extend posteriorly along the tentorial margin, with a dovetail appearance. The extra-axial mass is noncystic and heterogeneous in texture, and on CT imaging reveals hyperostosis, blistering of the tuberculum and erosion of the dorsum sellae; on T1-weighted images, the lesions are isointense and on T2-weighted images isointense to slightly hypertense to brain, enhancing dramatically

These are the second most common form of pediatric suprasellar tumor, accounting for 25-30% of such cases. Bilateral optic nerve gliomas are associated with neurofibromatosis type I in 20-50% of these patients. On CT, the lesions are isodense to hypodense, and frequently enhance following contrast injection. On MRI, the lesions are hypointense on Tl-weighted images and hyperintense on T2-weighted images. The MRI may show no contrast enhancement, variable enhancement, or intense uniform enhancement. The contrast pattern does not correlate with the pathological grade of the tumors

These are midline tumors, found most commonly in the posterior fossa and only rarely in the suprasellar region. Imaging reflects the high fat content of these lesions. Calcification is relatively common. CT shows a hypodense lesion. The signals on MRI reflect a higher fat content than that of the brain. These tumors with the lipomas are two uncommon causes of suprasellar "bright spots"

These are located along the cisterns in the cerebel-lopontine angle, or in the parasellar area and elsewhere as in the fourth ventricle, lateral ventricles, cerebrum, cerebellum, and brain stem. On CT, epider-moids appear as low-density lesions that do not enhance with contrast. The MRI appearance is hypointense compared to brain on Tl-weighted images and hyperintense on the T2-weighted images

Found in the pineal region, intrasellar or suprasellar, and in the sacrococcygeal region. Teratomas include tissue from all three germ-cell layers. MRI demonstrates an infiltrating mass that is isointense to brain on Tl-weighted images, moderately hyperintense on proton density and T2-weighted images. Homogeneous enhancement is common in both CT and MRI studies

Epidermoid tumors ("pearly tumors")

Teratomas and teratoid tumors, including dys-germinomas

Lipomas

Metastases

- Hematogenous spread

- Perineural spread

Chondrosarcoma

Lymphoproliferative disorders - Lymphoma

- Granulocytic sarcoma or chloroma

Olfactory neuro-blastoma

Most intracranial lipomas are considered as congenital abnormalities rather than neoplasms. The most common sites are the interhemispheric fissure (50%), the quadrigeminal cistern and pineal region, the suprasellar cistern and cerebellopontine angle cistern. CT imaging shows attenuation values that are in the negative range, usually -30 to -100 HU, and are isodense to subcutaneous fat. MRI demonstrates lipomas high in intensity on Tl-weighted images and intermediate to low on T2-weighted images.

Represent approximately 1 % of sellar and parasellar masses.

The most frequent metastatic lesions in this region from systemic primary cancer come from lung, breast, and prostate.

• Head and neck tumors may demonstrate perineural spread through the foramen at the skull base into the brain; e.g., basal-cell carcinoma, melanoma, adenoid cystic carcinoma, schwannoma, lymphoma.

• Infections; e.g., actinomycosis, Lyme disease, herpes zoster. Metastases are typically isointense on Tl-weighted images and moderately hyperin-tense on T2-weighted images. Moderate enhancement occurs after gadolinium injection

Rare tumor arising from embryonal residues, endo-chondral bone, or cartilage and located at the skull base, parasellar region, in the meninges, or in the brain. CT demonstrates a mass (calcified in 60% of cases) and enhancing neoplastic tissue. MRI shows the enhanced mass. The CT is probably more specific for this tumor, because of its sensitivity to calcium

Intrasellar and suprasellar component. May involve the pituitary gland, hypothalamus, infundibular stalk in older adults

Primitive myeloid cell tumor; rarely involving the CNS

Trigeminal schwan- Rare tumors (0.4% of brain tumors), arising most noma commonly from the parasellar region of the Gasserian ganglion or the posterior fossa. On CT imaging, particularly with bone windows, erosion can be demonstrated at the petrous apex. On MRI, the lesions are smooth masses, isointense on T1-weighted images and with high intensity on T2-weighted images, with avid enhancement and intratumoral "cystic" changes observed within the enhancing mass

CNS: central nervous system; CT: computed tomography; HU: Hounsfield unit; MRI: magnetic resonance imaging.

Nonneoplastic Lesions (Fig. 2)

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