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Petechial Hemorrhages
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Petechial Hemorrhages

This is a lateral view of the brain with the frontal lobes to the left and the occipital lobes and cerebellum to the right.
The arrows point to numerous petechial hemorrhages which could be due to blood dyscrasias such as seen in terminal leukemias, ITP, etc. or due to toxins such as arsenic.
(Description By:Melinda Sanders, M.D. )
(Image Contrib. by:Melinda Sanders, M.D. UCHC )
Cerebral or cerebellar hemorrhage
Etiology

The most common cause of intraparenchymal hemorrhage is hypertension
Other causes include blood dyscrasias or rupture of vascular malformations.
Pathogenesis

Hypertensive hemorrhages are often due to hypertensive lipohyalinosis of of small arteries with formation of small Charcot-Bouchard aneurysms.
Blood dyscrasias cause bleeding due to inability of the blood to clot.
Hemorrhages from vascular malformations are caused by trauma or hypertension further damaging an abnormal blood vessel wall.,
Epidemiology

Eighty percent of intraparenchymal hemorrhages in the hypertensive are found in the basal ganglia, thalamus or white matter.
Ten percent are seen in the pons, and 10% in the cerebellar hemispheres. They are usually large and in 50% of cases cause death.
They may also rupture into the ventricle which may cause death or may be helpful in decompression.
Blood dyscrasias such as leukemias often produce many small petechial or larger hemorrhages.
Vascular malformations may rupture due to hypertension, trauma or abnormalities of the blood vessel wall.
General Gross Description

Intraparenchymal and intraventricular hemorrhages appear as a mass of blood in the brain tissue or ventricle.
The walls of a large hemorrhage thought to be due to hypertension should be examined for abnormal vessels. In blood dyscrasias, multiple smaller hemorrhages are scattered throughout the brain tissue. Usually a large hemorrhage is associated with asymmetrical edema and herniation of structures.
General Microscopic Description

Microscopically hemorrhages are surrounded by pallor of tissue, spongiosus, and pericellular vacuolization. If the patient survives the area of hemorrhage is walled off by reactive astrocytes and macrophages.
There is a collagenous capsule around an old hemorrhage with hemosiderin laden macrophages still present.
Clinical Correlation

Hypertensive hemorrhages are characterized by severe headache and hemiparesis with the rapid onset of coma. 50% of patients with hypertensive hemorrhages die within the first 48 hours.These same clinical signs can be seen with a ruptured vascular malformation if the hemorrhage is large enough.
Patients with intra-parenchymal hemorrhages due to blood dyscrasias are often moribund but some may survive depending on the size and position of the hemorrhages.
References

Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp.65-78,
Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp.1311-1312.
Cerebral or cerebellar hemorrhage
Synopsis by: Dr ML Grunnet (TX2000M37020)[559]
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