Headache, Seizures
Case History: 47-year-old male with headaches followed by generalized tonic-clonic convulsions.
Case History: 47-year-old male presented with complaints of headaches followed by episode of generalized tonic-clonic convulsions.
No associated history of fever, focal neurological deficit, or cranial nerve involvement. Patient was vegetarian with negative diabetes, hypertension, and HIV status.
Figure 1. T2 weighted (5120/105) non-contrast axial image showing well-defined lobulated hyperintense extra-axial lesion involving left frontal region producing mass effect inform of focal midline shift of anterior falx cerebri and compression of frontal horn of left lateral ventricle. Note the CSF space surrounding the lesion defining its extra-axial nature.
Figure 2. T1 weighted (700/50) non-contrast axial image (A) at bithalamic levels showing above mentioned lesion (black thick arrow) to follow fat intensity and (B) at the level of mammillary bodies showing “spillage” of above mentioned fat intensity in bilateral basal cisterns (right > left) (black thin arrow).
Figure 3. A, T2 weighted (5120/105) non-contrast sagittal image showing hyperintense extra-axial lesion situated at anterior cranial fossa causing scalloping of anterior aspect of left greater wing of sphenoid. The altered signal intensity also extends into suprasellar cistern (thin black arrow) suggesting its rupture into subarachnoid space. B, Non-contrast CT scan sagittal image showing foci of calcification along periphery of fat density lesion suggestive of dermoid cyst.
Figure 4. T2 weighted gradient image (938/15) shows marked susceptibility artifacts within the lesion, suggestive of calcification which was confirmed on non-contrast CT scan.
Figure 5. T1 weighted (700/50) non-contrast fat supressed axial image showing near complete supression of above described T1-weighted and T2-weighted hyperintensity, suggesting fatty nature.
Diagnosis: Intracranial dermoid with rupture into subarachnoid space.
If rupture occurs, aseptic chemical meningitis may ensue with profound irritative effects from the disseminated cholesterol debris.
On MRI scans, dermoids will be hyperintense (bright) on T1-weighted imaging and heterogenous on T2-weighted imaging.
When a dermoid tumor ruptures, fat droplets - appearing hypodense on CT or T1 hyperintense on MRI - may be seen scattered and floating within the nondependent portions of the ventricular system and/or subarachnoid space.
