One of the main teaching points of this case is to not overlook the initial hyperdense lesion on CT scan as demonstrating hemorrhage. Not only is the anterior temporal region unusual for spontaneous hemorrhage, the considerable amount of surrounding edema, as well as the patient's young age must warrant further investigation. Classically, hyperdense lesions on CT scan without contrast administration which aren't obviously calcified are thought to represent acute blood products. However, one must remember that very cellular tumors can be spontaneously dense relative to normal cortex.

The differential diagnosis for the CT appearance is broad, but might include:

• Hematoma (e.g. from amyloid angiopathy, venous sinus thrombosis, vasculitis)
• Tumor, either hemorrhagic or non-hemorrhagic but hypercellular (e.g. glioblastoma, metastases, lymphoma/leukemia)
• Vascular malformation (e.g. cavernous or arteriovenous)
• Cerebral contusion
• Infectious (e.g. tuberculoma)

Subsequent biopsy revealed gliosarcoma.