Contributed by Peter Witt1, Judith Gault1, B. K. Kleinschmidt-DeMasters1,2,3
1Departments of Neurosurgery and Departments of 2Pathology and 3Neurology, University of Colorado Health Sciences Center, Denver, CO
CLINICAL HISTORY AND NEUROIMAGING:
The patient is a 23-year-old Hispanic male who suffered a first time, complex partial seizure followed by generalized tonic-clonic seizure. He was admitted to the hospital and was found to have right arm and leg weakness and dysesthesias. A CT scan of the head, performed soon after admission, showed a hemorrhagic left frontal lobe brain lesion. MRI scan demonstrated a slightly bilobed, 3 cm. in diameter lesion which was bright on pre-contrast T1-weighted scans and was located in the vertex of the left frontal lobe (Figure 1). The lesion did not enhance and had rings of low signal on T2-weighted scans, most consistent with a subacute to chronic intraparenchymal hematoma into which "bleeding may have occurred on more than one occasion" (Figure 2). The amount of edema was considered somewhat excessive given the size of the hematoma, but there was no midline shift (Figure 2). The MR angiogram failed to show any large feeding or draining vessels and there was no evidence of vascular abnormality or neoplasm. The circle of Willis showed a 1-2 mm. aneurysm in the proximal right middle cerebral artery before the bifurcation and there was thought to be duplication or fenestration of the anterior communicating artery.
Following resection of the clot, the patient did well on anti-seizure medications. Permission was obtained to perform genetic testing for cavernous malformations (CCM), especially given his Hispanic ethnicity and residence in southern Colorado, an area well known to have a large population of Spanish-Americans affected by familial cavernous angiomas. However, testing for the C1363T KRIT1 Hispanic-American mutation was negative.
Sections showed a resolving clot intimately admixed with intensely gliotic brain tissue that contained hemosiderin and bright yellow biliverdin deposits (Figure 3) and numerous CD-68 positive macrophages. Adjacent to the clot, there was profuse granulation tissue response, with intersecting Masson trichrome-positive fibrous strands (Figure 4). No underlying residual cavernous malformation or arteriovenous malformation could be recognized on trichrome or Verhoeff-van Gieson (VVG) elastic stains. The majority of the specimen was composed of a ball-like area of organizing clot admixed with large papillary formations (Figure 5) manifesting a fibrotic core and covered by variably plump, or attenuated, CD31-immunoreactive cells (Figure 6). There were very rare mitotic figures in the papillary vascular lesion (Figure 6), consistent with the highly reactive process. Immunostains for HHV-8 virus were negative.