This document discusses various masses that can occur in the cerebellopontine angle region as seen on magnetic resonance imaging. It provides 14 figures showing examples of different pathologies that can present in this area, such as acoustic neuromas, meningiomas, metastases, and aneurysms. Each figure includes one or more images of a lesion and provides a brief description and diagnosis. A variety of imaging characteristics are demonstrated, including signal intensity, enhancement patterns, and effects on surrounding structures.

1. 15Cerebellopontine Angle
Masses on Magnetic Resonance
Imaging

2. CLINICAL IMAGAGING
AN ATLAS OF DIFFERENTIAL DAIGNOSIS
EISENBERG
DR. Muhammad Bin Zulfiqar
PGR-FCPS III SIMS/SHL

3. • Fig SK 15-1 Acoustic neuroma. Marked contrast
enhancement of the left-sided lesion (arrowheads).
Note the normal neural structures on the right.

4. • Fig SK 15-2 Acoustic neuroma. Bilateral tumors
(n) are seen in this coronal scan of a patient
with neurofibromatosis.

5. • Fig SK 15-3 Meningioma. Note that the mass
(arrows) has a relatively broad base along the
petrous bone.

6. • Fig SK 15-4 Epidermoid. (A) Axial T1-weighted
and (B) axial T2-weighted scans show an
oblong mass (arrows) of slightly higher signal
than CSF enveloping the basilar artery and
extending around the pons.

7. • Fig SK 15-5 Lipoma. Axial T1-weighted image
shows that the lesion has signal intensity
similar to that of subcutaneous fat.25

8. • Fig SK 15-6 Metastasis. (A) Axial T2-weighted image
shows a metastasis of the right cerebellopontine angle
(from lung carcinoma) that mimics an acoustic
neuroma but is associated with unusual middle ear
retention (*). (B) Contrast-enhanced axial T1-weighted
scan shows intense enhancement of the lesion, which
extends into the cochlea (arrow). Note the presence of
another enhancing lesion at the tip of the right petrous
bone (arrowhead).25

9. • Fig SK 15-7 Arachnoid cyst. (A) Axial T1-
weighted image shows the CSF-intensity cyst
stretching the left 7th and 8th cranial nerve
complex (arrow). (B) Axial T2-weighted scan
shows the cyst displacing the vascular
structures of the cerebellopontine angle
(arrowheads).25

10. • Fig SK 15-8 Aneurysm of the left posterior inferior
cerebellar artery. Axial T2-weighted image shows the
typical lack of signal (arrow) within the aneurysm. Note the
lymphoma in the right pterygopalatine fossa (arrowheads),
which explained the patient's neuralgia.25

11. • Fig SK 15-9 Thrombosed aneurysm of the right
posterior inferior cerebellar artery. (A) Axial T2-
weighted image shows a focal area of calcification
(arrowhead). Note the normal right hypoglossal canal
(arrow), a finding inconsistent with an acoustic
neuroma. (B) Contrast coronal T1-weighted scan shows
homogeneous enhancement of the organized
thrombus, which completely fills the aneurysm.25

12. • Fig SK 15-10 Glomus jugulare tumor with intracranial
involvement and bony erosion. (A) Axial T1-weighted
image shows the mass (arrowheads) in the left
temporal bone and posterior fossa extending across
the midline. Note the large veins on the surface of the
tumor. (B) Coronal contrast-enhanced image shows
displacement of the brainstem, bony erosion from the
large enhanced mass, and parotid involvement.26

13. • Fig SK 15-11 Brainstem glioma. A contrast axial
T1-weighted image shows central enhancement
in an unusual round grade III glioma located in
front of the porus.25

14. • Fig SK 15-12 Hemangioblastoma. (A) Axial T2-
weighted image in a patient with von Hippel-
Lindau disease shows a solid tumor in the left
cerebellopontine angle. Note the vascular pedicle
(arrowhead), which appears as a flow void with
all sequences. (B) Contrast T1-weighted axial
image shows homogeneous enhancement of the
tumor (arrowhead).25

15. • Fig SK 15-13 Choroid plexus papilloma. (A) Axial T2-
weighted image shows a right cerebellopontine angle
papilloma extending through the foramen of Luschka. The
tumor contains massive hypointense calcification
(arrowhead). (B) Contrast T1-weighted axial scan shows
intense enhancement of the hypervascularized tumor. Note
the normal choroid plexus in the left foramen of Luschka.25

16. • Fig SK 15-14 Chondrosarcoma. (A) Axial T1-
weighted image shows the large tumor with
its skull base pedicle. (B) Contrast T1-weighted
coronal scan shows punctate enhancement,
which could suggest a chondromatous
lesion.20

17. • Fig SK 15-15 Trigeminal neuroma. Isointense
mass on the right (arrow). Note the normal
5th cranial nerve on the left (arrowhead).