Stroma is the connective tissue just below the surface of an organ. Stroma is a special type of tissue that helps hold the other parts of the organ together.
Stroma is made up of cells that give the tissue its strength and shape. Many of these cells are called fibroblasts and pathologists often describe them as spindle cells because they are long and thin. The stroma also includes blood vessels that bring nutrients to the tissue and lymphatic channels that remove excess fluid and waste.
The way stroma looks when viewed under the microscope changes in response to injury or or cancer. Desmoplasia is a word pathologists use to describe the look of the stroma after cancer cells have entered the tissue. The movement of cancer cells into a tissue is called invasion and pathologists look for desmoplasia when trying to decide if a tumour is benign or malignant.