When mast cells, usually from bone marrow, skin, and GI biopsies, are exposed to a special dye in pathology labs the granules of the mast cell or their cartilage matrix shows up in a distinctive purple colour.
Once mast cells are highlighted in purple, pathologists and hematologists can use a microscope to assess the number of cells in a sample. They can also see mast cells activated by triggers such as physiological mediators, allergens and other pathogens.
Establishing the density of the mast cell population and seeing the level of degranulation, along with other things like easily establishing the shapes and sizes of mast cells, are key for the diagnosis of many mast cell diseases.
The images of mast cell slides from a patient’s biopsy are often synonymous with the first time someone hears their diagnosis, after a considerable period of uncertainty and declining health.
For these practical and deeply emotive reasons, purple is the international colour for Mastocytosis and Mast Cell Diseases Day, as well as the brand colour for TAMS.