microinvasion

[mī′krō-ĭn-vāzhən]
n.
  1. Invasion of in situ carcinoma into tissue that is immediately adjacent, being the earliest stage of malignant neoplastic invasion.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.