Cytology is the study of individual cells of the body, as opposed to histology which is the study of whole human tissue itself. Strictly speaking, cytology is the study of normal cells and cytopathology is the examination of cells in the context of disease, which is really what we’ll be talking about but “cytology” is used by many people as shorthand for both, so that’s what we’ll do here. The human body is made up of millions of cells and these can be sampled and looked at under the microscope, after suitable preparation, to help diagnose medical conditions.
This involves looking at the individual cells for abnormal changes of both the nucleus and also the cytoplasm (body) of the cell. The nucleus contains the genetic material that controls the cell, and determines what type of cell it will become, but also controls its behavior. Changes in the nucleus, gauged by changes in its size, shape and appearance of the nuclear material (chromatin) can be assessed by a trained cytologist and this can be used to diagnose possible cancer and also pre-cancer. “Pre-cancer” means cell changes which if left untreated may develop into a true cancer. Cytology can also be used to diagnose many non-cancerous medical conditions such as infections and systemic diseases.