Imaging MR – large suprasellar mass with predominantly multilobulated cystic components and smaller nodular components measuring approximately 3.4 x 2.8 by 3.3 cm. Irregular peripheral enhancement. DDX – Craniopharyngioma, hypothalamic astrocytoma
Microscopy shows Rosenthal fibers and elongated astrocytic process typical of pilocytic astrocytoma. Note loose and dense cellular areas.
Optic pathway gliomas Optic pathway gliomas represent 3% to 5% of childhood brain tumors. Majority of optic chiasmatic-hypothalamic gliomas (OCHGs) are pilocytic astrocytomas. In patients with neurofibromatosis, OCHGs most commonly involve the intra-orbital optic nerve (66%), followed by the chiasm (62%). In patients without neurofibromatosis, OCHGs most commonly involve the chiasm (91%), with the optic nerves involved in 32% of OCHGs. In one study of 24 patients, optic chiasm involved in 100% of cases, hypothalamus in 89%, optic chiasm alone in 11%, optic tracts in 28%, and optic nerve in 11%. Differential diagnosis of sellar-suprasellar lesions includes pituitary adenoma, meningioma, germinoma, craniopharyngioma, Rathke cleft cyst, dermoid cyst, tuberculoma, and sarcoidosis. It is not always possible to distinguish craniopharyngiomas from OCHGs by MRI. Bommakanti K,, et al. Optic chiasmatic-hypothalamic gliomas: Is tissue diagnosis essential? Neurol India, 2010;58(6):833-40.
Case #2 48 y/o male with RUE/RLE numbness for 8 months. Imaging was performed, identifying a cervical spinal cord lesion.
MR Imaging Expansion of cervical cord by a T2 hyperintense intramedullary mass. Areas of intense enhancement within the intramedullary mass, some rim-like & also cystic areas within the mass. DDX: ependymoma or astrocytoma
Mild hypercellularity and Rosenthal fibers are compatible with pilocytic astrocytoma.
Pilocytic astrocytoma of the spinal cord Spinal cord pilocytic astrocytomas (PA) are uncommon tumors that account for 21% of intramedullary glial tumors affecting children and young adults. Although rare, PAs are the most frequent spinal cord tumors in the pediatric population, and second only to ependymomas in adults. Unlike brain astrocytomas, spinal cord astrocytomas usually are low-grade lesions. Most spinal cord PAs are already large at presentation, as they grow insidiously and evolve often over months or years without clearly defined neurologic deficits. PAs usually occur in thoracic spine region, followed by cervical and lumbar regions. Regional back pain is most common initial complaint. Sensory disturbances and loss of sensation occur frequently. Later, spasticity and weakness with loss of bowel and bladder function occurs. Horger M, et al. Spinal pilocytic astrocytoma: MR imaging findings at first presentation and following surgery. European Journal of Radiology, 2011; 79:389– 399.
Astrocytoma of the Spinal Cord T1 – Cord expansion, less than 4 segments – Multi-segmented more common with pilocytic T2 – Hyperintense Post Contrast – Almost always enhances Diffuse fibrillary > pilocytic
Case #3 21 month old girl found unresponsive. Several episodes of vomiting that self resolved 2- wks prior. Fussy through the night with difficulty sleeping. Slept longer than normal in morning, found unresponsive.
MR Imaging Large parieto-occipital mass measuring 8.5 x 6.8 x 7.3 cm with mass effect. Hyperintense intratumoral signal from blood products and calcium is identified. Little enhancement. DDX: – supratentorial ependymoma, atypical rhadboid teratoid tumor or supratentorial PNET
Supratentorial Ependymoma CT – Solid and cystic with hemorrhage and calcifications T1: – Usually iso to hypo, hyperintense Ca, blood products T2: – Strikingly hyperintense cystic foci FLAIR: – Sharp tumor interface DWI: – Similar to surrounding parenchyma Post-Contrast: – Mild to moderate enhancement