The patient went onto have the clot evacuated and a small sample of tissue sent to histology. 

Histology

Sections show abundant fresh blood clot, containing layers of degenerating neutrophils and fibrin alternating with red cells. There is an accumulation of blood beneath the leptomeninges, which contain scattered vessels of varying caliber showing mural thickening with some luminal narrowing, and amorphous eosinophilic material within the wall that is strongly suggestive of amyloid. Congo red stains this material, which shows apple-green birefringence on polarization.

A small fragment of edematous cortex and white matter is sampled. This shows a mild astrocytosis. Only small capillary-sized vessels are seen, however, these are normal in appearance. There is no evidence of a vascular malformation.

FINAL DIAGNOSIS: Intracerebral hematoma, cortex over frontal cerebral hematoma and leptomeningeal vessels showing amyloid angiopathy.

Discussion

Lobar hemorrhages are typically seen in elderly patients and in most cases attributable to cerebral amyloid angiopathy. In young patients, a lobar hemorrhage should be viewed with suspicion and an underlying lesion sought.