progressive vaccinia

n.

A severe or even fatal form of vaccinia occurring as a complication of smallpox vaccination chiefly in persons with an immunologic deficiency or dyscrasia, characterized by progressive enlargement of the initial and secondary lesions.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.