Papillary describes cells that are sticking together to create long finger-like projections of tissue. The cells are seen on the outside surface of the tissue while small blood vessels are 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.