CLASSIFICATION AND HISTOPATHOLOGIC SPECTRUM OF CENTRAL NERVOUS SYSTEM VASCULITIS

Vasculitis, or angiitis, is defined as an inflammatory disease of arteries, veins, or both of all sizes that results in histologically demonstrable structural injuries to the vessel walls, often accompanied by thrombosis and evidence of ischemic damage to the organ-tissues served by the affected blood vessels. A vasculitis is considered primary when it occurs without an identifiable cause or unassociated with an underlying disease; and secondary when it occurs as a manifestation of i diverse group of underlying diseases, including mal ignancie~ .~ ' ,~~ ,~~ The Central Nervous System may be the seat of a wide variety of vasculitides, most of which are associated with a known underlying disease (secondary CNS angiitis), vasculitis of unknown etiology and predominantly affecting the CNS (primary CNS angiitis), in comparison, is quite rare; there are also a host of nonvasculitic conditions that may mimic the primary or secondary CNS angiitis clinically, angiographically, and, sometimes, even histopathologically, and these are the CNS vasculitis look-alikes and simulators (Table 1).4,23,24,29,30,39,45