Granulomatous angiitis

# Overview
Granulomatous angiitis is an uncommon necrotizing vasculitis of unknown cause that is restricted to vessels of the central nervous system.

# Historical Perspective
Cravioto and Feigin defined granulomatous angiitis in 1959.

# Pathophysiology
The pathophysiologic effect of granulomatous angiitis seems to be the alteration of the permeability of vessel walls.  This change in permeability leads to the leaking of cells and proteins into the surrounding structures, causing subsequent edema.

## Microscopic Pathology
- It mainly involves small intracerebral vessels.
- Microscopic changes include
Focal fibrinoid necrosis of the vessel wall
Variable inflammatory infiltrate (neutrophils, lymphocytes, epitheloid appearing histiocytes and multinucleated giant cells) form granulomas in the wall of the vessel.
Ischemic or hemorrhagic changes may be seen in the parenchyma distal to the segment involved.
- Focal fibrinoid necrosis of the vessel wall
- Variable inflammatory infiltrate (neutrophils, lymphocytes, epitheloid appearing histiocytes and multinucleated giant cells) form granulomas in the wall of the vessel.
- Ischemic or hemorrhagic changes may be seen in the parenchyma distal to the segment involved.

# Causes
The exact causes of granulomatous angiitis are obscure, but a few associations have been established:
- Herpes zoster
- Hodgkin lymphoma

# Differentiating Granulomatous Angiitis from other Diseases
A few vasculitides have to be differentiated from granulomatous angiitis.  They include:
- Periarteritis nodosa
- Takayasu disease
- Temporal arteritis
- Sarcoidosis
- Allergic granulomatous arteritis
Distinguishing features of granulomatous angiitis include:
- Perivascular chronic inflammatory cells
- Presence of fibrinoid necrosis around the intracerebral vessels
- Allergic arteritis is excluded by absence of history of atopy and eosinophillia
- Localization only to intracerebral vessels excludes systemic disease like sarcoidosis
On a CT head scan, granulomatous anigiitis presents as a non contrast enhancing lesion which may be misinterpreted as an intracranial lesion resulting from:
- Cerebral infarction
- CNS infections
- Primary brain tumors
- Metastatic brain lesions
- Progressive multifocal leukoencephalopathy
- Demylineating diseases (multiple sclerosis)

# Epidemiology and Demographics
Very few cases of granulomatous angiitis have been reported.

## Age
- This disease is more common in middle aged and elderly individuals.

## Gender
- Gender is not associated with an increased risk of granulomatous angiitis.

## Race
- Race is not associated with an increased risk of granulomatous angiitis.

# Natural History, Complications and Prognosis
The clinical course is usually progressive with occasional temporary remissions.  It progresses to death within a year.

# Diagnosis

## History
- History of Herpes zoster infection
- History of any lymphomas such as Hodgkin lymphoma

## Symptoms
- Confusion
- Focal cerebral symptoms

## Physical Examination

### Neurologic
- Altered consciousness
- Unexplained fall
- Intellectual deterioration

## Laboratory Findings

### Electrolyte and Biomarker Studies
- Complete blood count, differential count to rule out infections.
- Levels of calcium, magnesium, and glucose to differentiate from metabolic causes of confusion and encephalopathy.
- Elevated levels of ESR, and CRP can be noticed.

### CT Scan
- A CT head scan may show a few features of diffuse, bilateral, poorly defined, or non-contrasting low density areas.
These finding are highly suggestive of granulomatous angiitis .
- These finding are highly suggestive of granulomatous angiitis .
- Cerebral edema may be evident.
- A few areas of ischemia may be noticed distal to the segment involved.

### Biopsy
- Cerebral biopsy is not routinely done.
- It has a low diagnostic accuracy due to these aspects of granulomatous angiitis"
Segmental nature of the lesion in the cerebral vessels
Rarity of lesion
Lack of supporting strong radiologic findings.
- Segmental nature of the lesion in the cerebral vessels
- Rarity of lesion
- Lack of supporting strong radiologic findings.

# Treatment

## Pharmacotherapy
- A corticosteroid therapy is used to reduce cerebral edema
- A combination of chemotherapy, radiotherapy, and steroids is used in cases of Hodgkins lymphoma.
This therapy may result in complete clinical and radiological remission of the disease.
- This therapy may result in complete clinical and radiological remission of the disease.