Primary Angiitis of the CNS (PACNS)

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Background    Neuroimaging   Histopathology & Immunohistochemistry

BACKGROUND AND CLINICAL INFORMATION: Head  

Summary: PACNS is a non-infectious angiitis of the CNS that carry grave prognosis. They are rare and most commonly seen in the 4^th to 6^th decade. The patients present with a variety of focal neurologic deficits. The histopathology is variable. It can present as granulomatous or non-granulomatous angiitis. Giant cells may be seen are are intimately associated with or contain fragments of the internal elastic lamina.

Other Name: Formerly known as non-infectious granulomatous angiitis of the CNS, isolated angiitis, primary vasculatitis of the CNS. 

Incidence: rare. Clinical picture is vague and non-specific.

Age: usually adults (30-50 y/o).

Lab.: ESR is usually normal or at most mildly elevated. CSF may have a picture of aseptic meningitis.

Negative biopsy does not necessarily exclude the possibility of PACNS.

Clinical:  The majority of patients develop a variety of focal neurologic deficits, but this occurs mostly in the presence of some element of diffuse neurologic dysfunction, such as decreased mentation or altered level of consciousness.

• The mean duration of symptoms before diagnosis is about 5 months.

NEUROIMAGING: Head  

Demonstration of multiple narrowed segments in cerebral arteries is suggestive but not diagnostic for PACNS.

HISTOPATHOLOGY AND IMMUNOHISTOCHEMISTRY: Head  

Biopsy site: 

• The best sample is a wedge biopsy from cerebral cortex with the leptomeninges included.

• The leptomeninges is usually involved. Vasculitis may be seen only in parenchyma or leptomeninges or both.

• The brain is the primary site but the spinal cord can also be involved. Affected vessels: Small arteries (200-500 micron) are most affected. Veins are less frequently affected than arteries.

Histopathology is varied:

• It can present as granulomatous or non-granulomatous form. The non-granulomatous form can present as PAN type necrotizing inflammation or as simple lymphocitic vasculitis. The inflammatory infiltration is composed mainly of lymphocytes accompanied by histiocytes and plasma cells. There is a variable amount of fibrinoid necrosis.

• Giant cells are intimately associated with or contain fragments of the internal elastic lamina.

• The intima or the media or both may be involved. The adventitia is generally thickened and contains inflammatorycells that spill into and expand the surrounding arachnoid space.

NeuroLearn NeuroHelp Vascular  For Comment: KarMing-Fung@ouhsc.edu

Background    Neuroimaging   Histopathology & Immunohistochemistry