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From the Archives of the AFIP

Pilocytic Astrocytoma: Radiologic-Pathologic Correlation¹

¹ From the Departments of Radiologic Pathology (K.K.K.) and Neuropathology (E.J.R.), Armed Forces Institute of Pathology, 14th St at Alaska Ave, Bldg 54, Rm M-121, Washington, DC 20306-6000; Department of Radiology and Radiological Sciences, Uniformed Services University of the Health Sciences, Bethesda, Md (K.K.K.); and Department of Pathology, George Washington University, Washington, DC (E.J.R.). Received July 19, 2004; revision requested August 20 and received September 7; accepted September 7. Both authors have no financial relationships to disclose. Address correspondence to K.K.K. (e-mail: koeller@afip.osd.mil).

View larger version (180K): [in a new window]   Figure 1.  Pilocytic astrocytoma. Photomicrograph (original magnification, x40; hematoxylin-eosin stain) of a classic pilocytic astrocytoma reveals a biphasic appearance with a loose glial component (g) with numerous microcysts and vacuoles and more compact piloid tissue (p) with elongated bipolar cells (arrowhead) showing fine fibrillary processes. Rosenthal fibers (arrows) are also noted.

View larger version (110K): [in a new window]   Figure 2a.  Cerebellar pilocytic astrocytoma. (a) Axial CT image shows a well-marginated mass of the right cerebellar hemisphere. The mass has both cystic (c) and soft-tissue (s) components. (b) Axial T2-weighted image reveals predominant hyperintensity within the mass with slightly lower signal intensity of the soft-tissue component. (c) Contrast material-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule and lack of enhancement of the cystic portion. (d) Intraoperative photograph shows the smooth margin of the cystic portion (c).

View larger version (129K): [in a new window]   Figure 2b.  Cerebellar pilocytic astrocytoma. (a) Axial CT image shows a well-marginated mass of the right cerebellar hemisphere. The mass has both cystic (c) and soft-tissue (s) components. (b) Axial T2-weighted image reveals predominant hyperintensity within the mass with slightly lower signal intensity of the soft-tissue component. (c) Contrast material-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule and lack of enhancement of the cystic portion. (d) Intraoperative photograph shows the smooth margin of the cystic portion (c).

View larger version (172K): [in a new window]   Figure 2c.  Cerebellar pilocytic astrocytoma. (a) Axial CT image shows a well-marginated mass of the right cerebellar hemisphere. The mass has both cystic (c) and soft-tissue (s) components. (b) Axial T2-weighted image reveals predominant hyperintensity within the mass with slightly lower signal intensity of the soft-tissue component. (c) Contrast material-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule and lack of enhancement of the cystic portion. (d) Intraoperative photograph shows the smooth margin of the cystic portion (c).

View larger version (169K): [in a new window]   Figure 2d.  Cerebellar pilocytic astrocytoma. (a) Axial CT image shows a well-marginated mass of the right cerebellar hemisphere. The mass has both cystic (c) and soft-tissue (s) components. (b) Axial T2-weighted image reveals predominant hyperintensity within the mass with slightly lower signal intensity of the soft-tissue component. (c) Contrast material-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule and lack of enhancement of the cystic portion. (d) Intraoperative photograph shows the smooth margin of the cystic portion (c).

View larger version (120K): [in a new window]   Figure 3a.  Pilocytic astrocytoma with hemorrhage in an 11-year-old girl with onset of headache, nausea, and vomiting. Within 24 hours, the patient was obtunded and unresponsive. (a) Axial CT image shows hyperattenuation (arrow) consistent with hemorrhage within a vermian mass that effaces the fourth ventricle. (b) Photograph of a cut cerebellum specimen reveals a large hemorrhagic mass (m). Findings from histologic analysis confirmed pilocytic astrocytoma with hemorrhage.

View larger version (111K): [in a new window]   Figure 3b.  Pilocytic astrocytoma with hemorrhage in an 11-year-old girl with onset of headache, nausea, and vomiting. Within 24 hours, the patient was obtunded and unresponsive. (a) Axial CT image shows hyperattenuation (arrow) consistent with hemorrhage within a vermian mass that effaces the fourth ventricle. (b) Photograph of a cut cerebellum specimen reveals a large hemorrhagic mass (m). Findings from histologic analysis confirmed pilocytic astrocytoma with hemorrhage.

View larger version (138K): [in a new window]   Figure 4a.  Supratentorial pilocytic astrocytoma of the temporal lobe. (a) Axial CT image shows a hypoattenuated mass (m) of the right temporal lobe and a soft-tissue mural nodule (n) along its lateral margin. (b) Axial T1-weighted image reveals hypointensity of the mass with slightly higher signal intensity of the mural nodule. (c) Axial T2-weighted image demonstrates predominant hyperintensity of the mass with lower signal intensity of the mural nodule. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mural nodule. Signal intensity of the cyst is higher than that of cerebrospinal fluid within the lateral ventricles, a finding indicative of hemorrhagic or proteinaceous content. (e) Photograph of the resected mural nodule reveals a hemorrhagic mass.

View larger version (137K): [in a new window]   Figure 4b.  Supratentorial pilocytic astrocytoma of the temporal lobe. (a) Axial CT image shows a hypoattenuated mass (m) of the right temporal lobe and a soft-tissue mural nodule (n) along its lateral margin. (b) Axial T1-weighted image reveals hypointensity of the mass with slightly higher signal intensity of the mural nodule. (c) Axial T2-weighted image demonstrates predominant hyperintensity of the mass with lower signal intensity of the mural nodule. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mural nodule. Signal intensity of the cyst is higher than that of cerebrospinal fluid within the lateral ventricles, a finding indicative of hemorrhagic or proteinaceous content. (e) Photograph of the resected mural nodule reveals a hemorrhagic mass.

View larger version (124K): [in a new window]   Figure 4c.  Supratentorial pilocytic astrocytoma of the temporal lobe. (a) Axial CT image shows a hypoattenuated mass (m) of the right temporal lobe and a soft-tissue mural nodule (n) along its lateral margin. (b) Axial T1-weighted image reveals hypointensity of the mass with slightly higher signal intensity of the mural nodule. (c) Axial T2-weighted image demonstrates predominant hyperintensity of the mass with lower signal intensity of the mural nodule. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mural nodule. Signal intensity of the cyst is higher than that of cerebrospinal fluid within the lateral ventricles, a finding indicative of hemorrhagic or proteinaceous content. (e) Photograph of the resected mural nodule reveals a hemorrhagic mass.

View larger version (129K): [in a new window]   Figure 4d.  Supratentorial pilocytic astrocytoma of the temporal lobe. (a) Axial CT image shows a hypoattenuated mass (m) of the right temporal lobe and a soft-tissue mural nodule (n) along its lateral margin. (b) Axial T1-weighted image reveals hypointensity of the mass with slightly higher signal intensity of the mural nodule. (c) Axial T2-weighted image demonstrates predominant hyperintensity of the mass with lower signal intensity of the mural nodule. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mural nodule. Signal intensity of the cyst is higher than that of cerebrospinal fluid within the lateral ventricles, a finding indicative of hemorrhagic or proteinaceous content. (e) Photograph of the resected mural nodule reveals a hemorrhagic mass.

View larger version (129K): [in a new window]   Figure 4e.  Supratentorial pilocytic astrocytoma of the temporal lobe. (a) Axial CT image shows a hypoattenuated mass (m) of the right temporal lobe and a soft-tissue mural nodule (n) along its lateral margin. (b) Axial T1-weighted image reveals hypointensity of the mass with slightly higher signal intensity of the mural nodule. (c) Axial T2-weighted image demonstrates predominant hyperintensity of the mass with lower signal intensity of the mural nodule. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mural nodule. Signal intensity of the cyst is higher than that of cerebrospinal fluid within the lateral ventricles, a finding indicative of hemorrhagic or proteinaceous content. (e) Photograph of the resected mural nodule reveals a hemorrhagic mass.

View larger version (152K): [in a new window]   Figure 5a.  Classic appearance of a cerebellar pilocytic astrocytoma. (a) Axial T2-weighted image shows a hyperintense mass (m) of the left cerebellar hemisphere with a less intense soft-tissue nodule (n) along its posterolateral margin. Note absence of surrounding vasogenic edema. (b) Contrast-enhanced coronal T1-weighted image demonstrates intense enhancement of the mural nodule.

View larger version (161K): [in a new window]   Figure 5b.  Classic appearance of a cerebellar pilocytic astrocytoma. (a) Axial T2-weighted image shows a hyperintense mass (m) of the left cerebellar hemisphere with a less intense soft-tissue nodule (n) along its posterolateral margin. Note absence of surrounding vasogenic edema. (b) Contrast-enhanced coronal T1-weighted image demonstrates intense enhancement of the mural nodule.

View larger version (168K): [in a new window]   Figure 6a.  Atypical appearance of a supratentorial pilocytic astrocytoma with prominent vasogenic edema. (a) Sagittal T1-weighted image shows a large supratentorial mass with a soft-tissue component (s) in the region of the lateral ventricle trigone and cystlike regions (c) located more superiorly and anteriorly. (b) Axial T2-weighted image demonstrates extreme hyperintensity of the cystlike portions (c) and more mild hyperintensity of the soft-tissue mass (s) within the lateral ventricle. Note vasogenic edema around the mass (arrows). Vasogenic edema is not a common feature of pilocytic astrocytomas. (c) Contrast-enhanced axial T1-weighted image reveals intense enhancement of the soft-tissue portion and lack of enhancement of the cystic portion.

View larger version (132K): [in a new window]   Figure 6b.  Atypical appearance of a supratentorial pilocytic astrocytoma with prominent vasogenic edema. (a) Sagittal T1-weighted image shows a large supratentorial mass with a soft-tissue component (s) in the region of the lateral ventricle trigone and cystlike regions (c) located more superiorly and anteriorly. (b) Axial T2-weighted image demonstrates extreme hyperintensity of the cystlike portions (c) and more mild hyperintensity of the soft-tissue mass (s) within the lateral ventricle. Note vasogenic edema around the mass (arrows). Vasogenic edema is not a common feature of pilocytic astrocytomas. (c) Contrast-enhanced axial T1-weighted image reveals intense enhancement of the soft-tissue portion and lack of enhancement of the cystic portion.

View larger version (135K): [in a new window]   Figure 6c.  Atypical appearance of a supratentorial pilocytic astrocytoma with prominent vasogenic edema. (a) Sagittal T1-weighted image shows a large supratentorial mass with a soft-tissue component (s) in the region of the lateral ventricle trigone and cystlike regions (c) located more superiorly and anteriorly. (b) Axial T2-weighted image demonstrates extreme hyperintensity of the cystlike portions (c) and more mild hyperintensity of the soft-tissue mass (s) within the lateral ventricle. Note vasogenic edema around the mass (arrows). Vasogenic edema is not a common feature of pilocytic astrocytomas. (c) Contrast-enhanced axial T1-weighted image reveals intense enhancement of the soft-tissue portion and lack of enhancement of the cystic portion.

View larger version (123K): [in a new window]   Figure 7a.  Pilocytic astrocytoma with ringlike enhancement. (a) Axial T1-weighted image shows a hypointense mass (m) of the left cerebellar hemisphere. (b) Axial T2-weighted image reveals hyperintensity with numerous hypointense septations within most of the mass. (c) Contrast-enhanced axial T1-weighted image demonstrates ringlike enhancement of multiple cystic areas within the tumor.

View larger version (121K): [in a new window]   Figure 7b.  Pilocytic astrocytoma with ringlike enhancement. (a) Axial T1-weighted image shows a hypointense mass (m) of the left cerebellar hemisphere. (b) Axial T2-weighted image reveals hyperintensity with numerous hypointense septations within most of the mass. (c) Contrast-enhanced axial T1-weighted image demonstrates ringlike enhancement of multiple cystic areas within the tumor.

View larger version (109K): [in a new window]   Figure 7c.  Pilocytic astrocytoma with ringlike enhancement. (a) Axial T1-weighted image shows a hypointense mass (m) of the left cerebellar hemisphere. (b) Axial T2-weighted image reveals hyperintensity with numerous hypointense septations within most of the mass. (c) Contrast-enhanced axial T1-weighted image demonstrates ringlike enhancement of multiple cystic areas within the tumor.

View larger version (126K): [in a new window]   Figure 8a.  Pilocytic astrocytoma with solid enhancement. (a) Sagittal T1-weighted image shows a well-circumscribed, hypointense cerebellar mass (m). (b) Axial T2-weighted image shows the hyperintense mass of the cerebellar vermis and right cerebellar hemisphere. (c) Contrast-enhanced sagittal T1-weighted image demonstrates homogeneous enhancement of the mass.

View larger version (129K): [in a new window]   Figure 8b.  Pilocytic astrocytoma with solid enhancement. (a) Sagittal T1-weighted image shows a well-circumscribed, hypointense cerebellar mass (m). (b) Axial T2-weighted image shows the hyperintense mass of the cerebellar vermis and right cerebellar hemisphere. (c) Contrast-enhanced sagittal T1-weighted image demonstrates homogeneous enhancement of the mass.

View larger version (117K): [in a new window]   Figure 8c.  Pilocytic astrocytoma with solid enhancement. (a) Sagittal T1-weighted image shows a well-circumscribed, hypointense cerebellar mass (m). (b) Axial T2-weighted image shows the hyperintense mass of the cerebellar vermis and right cerebellar hemisphere. (c) Contrast-enhanced sagittal T1-weighted image demonstrates homogeneous enhancement of the mass.

View larger version (114K): [in a new window]   Figure 9a.  Exophytic pilocytic astrocytoma arising from the brainstem. (a) Axial CT image shows a hypoattenuated mass (m) of the posterior margin of the mid-pons and left cerebellar hemisphere. (b) Axial T2-weighted image reveals heterogeneous hyperintensity of the mass, which extends into the adjacent cisternal space (arrow). (c) Contrast-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule (n) and lack of enhancement of the cystic portion. Extension into the cerebellopontine cistern is again noted.

View larger version (127K): [in a new window]   Figure 9b.  Exophytic pilocytic astrocytoma arising from the brainstem. (a) Axial CT image shows a hypoattenuated mass (m) of the posterior margin of the mid-pons and left cerebellar hemisphere. (b) Axial T2-weighted image reveals heterogeneous hyperintensity of the mass, which extends into the adjacent cisternal space (arrow). (c) Contrast-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule (n) and lack of enhancement of the cystic portion. Extension into the cerebellopontine cistern is again noted.

View larger version (133K): [in a new window]   Figure 9c.  Exophytic pilocytic astrocytoma arising from the brainstem. (a) Axial CT image shows a hypoattenuated mass (m) of the posterior margin of the mid-pons and left cerebellar hemisphere. (b) Axial T2-weighted image reveals heterogeneous hyperintensity of the mass, which extends into the adjacent cisternal space (arrow). (c) Contrast-enhanced axial T1-weighted image demonstrates intense enhancement of the soft-tissue nodule (n) and lack of enhancement of the cystic portion. Extension into the cerebellopontine cistern is again noted.

View larger version (115K): [in a new window]   Figure 10a.  Pilocytic astrocytoma of the optic nerve. (a) Coronal T1-weighted image shows enlargement (arrow) of the left optic nerve within the intraconal compartment. (b) Axial T1-weighted image reveals characteristic kinking (arrowhead) of the enlarged left optic nerve. (c) Axial proton-density-weighted image demonstrates mild hyperintensity of the mass. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mass. (e) Photograph of the resected optic nerve mass reveals a well-circumscribed sausagelike appearance.

View larger version (111K): [in a new window]   Figure 10b.  Pilocytic astrocytoma of the optic nerve. (a) Coronal T1-weighted image shows enlargement (arrow) of the left optic nerve within the intraconal compartment. (b) Axial T1-weighted image reveals characteristic kinking (arrowhead) of the enlarged left optic nerve. (c) Axial proton-density-weighted image demonstrates mild hyperintensity of the mass. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mass. (e) Photograph of the resected optic nerve mass reveals a well-circumscribed sausagelike appearance.

View larger version (117K): [in a new window]   Figure 10c.  Pilocytic astrocytoma of the optic nerve. (a) Coronal T1-weighted image shows enlargement (arrow) of the left optic nerve within the intraconal compartment. (b) Axial T1-weighted image reveals characteristic kinking (arrowhead) of the enlarged left optic nerve. (c) Axial proton-density-weighted image demonstrates mild hyperintensity of the mass. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mass. (e) Photograph of the resected optic nerve mass reveals a well-circumscribed sausagelike appearance.

View larger version (128K): [in a new window]   Figure 10d.  Pilocytic astrocytoma of the optic nerve. (a) Coronal T1-weighted image shows enlargement (arrow) of the left optic nerve within the intraconal compartment. (b) Axial T1-weighted image reveals characteristic kinking (arrowhead) of the enlarged left optic nerve. (c) Axial proton-density-weighted image demonstrates mild hyperintensity of the mass. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mass. (e) Photograph of the resected optic nerve mass reveals a well-circumscribed sausagelike appearance.

View larger version (88K): [in a new window]   Figure 10e.  Pilocytic astrocytoma of the optic nerve. (a) Coronal T1-weighted image shows enlargement (arrow) of the left optic nerve within the intraconal compartment. (b) Axial T1-weighted image reveals characteristic kinking (arrowhead) of the enlarged left optic nerve. (c) Axial proton-density-weighted image demonstrates mild hyperintensity of the mass. (d) Contrast-enhanced axial T1-weighted image shows intense enhancement of the mass. (e) Photograph of the resected optic nerve mass reveals a well-circumscribed sausagelike appearance.

View larger version (122K): [in a new window]   Figure 11.  Dissemination from a pilocytic astrocytoma following resection. Contrast-enhanced sagittal T1-weighted image of the brain shows diffuse enhancement (arrows) of the basilar cisternal spaces, with extension into the upper cervical spine. A cystlike mass (m) is seen anterior to the brainstem.