Pathology dictionary -
Papillary describes to a pattern of growth where groups of cells form long projections that look similar to the branches on a tree. The cells sit on the outside of the tissue and small blood vessels are usually seen on the inside.
The word micropapillary is used similarly to describe very small projections.
Many types of cancer show a papillary pattern of growth. Common examples include:
If cells growing in a papillary pattern are seen after a small sample of tissue is removed from your body in a procedure called a biopsy, your pathologist may perform a test called immunohistochemistry to learn more about the cells such as where the cells came from.