Figure 14-105.

Pyogranulomatous Vasculitis, Feline Infectious Peritonitis, Cat.

A, Ventral brain, cerebral vasculature of the circle of Willis. A white-yellow pyogranulomatous inflammation distorts and obscures the blood vessels. Lesions are attributed to viral induced inflammation that targets vessel walls (arrows). The character of the inflammatory response can vary from an exudate with accumulation of serous fluid and fibrin mixed with neutrophils and histiocytes to a reaction that is more pyogranulomatous, and in which commonly there are lymphocytes and plasma cells. The severity and magnitude of the lesion depicted here is much more dramatic than usual. B, A cross-sectional view of A. The pyogranuloma (arrows) is principally in the subarachnoid space and has compressed the adjacent cerebral cortex.

(A and B courtesy Dr. J. Sundberg, College of Veterinary Medicine, University of Illinois.)