Histopathology is the study of diseased tissue, such as tissue obtained through a biopsy, by a specialized doctor known as a pathologist. Samples of tissue are studied under a microscope in order to identify how a disease develops. The tissue sample goes through a special process so it can be analyzed on a slide, as opposed to cytopathology, where samples are examined without being processed.
Samples for histopathology must be processed and fixed for examination. Two processes are used. The first is a chemical fixation procedure in which the tissue samples are immersed in a bath of paraffin, or wax, over a 12- to 16-hour period. This allows the tissue to be sliced into two to seven micrometer sections for examination.
The second process used is frozen sectioning. Tissue samples are frozen and sliced thin, as in the chemical fixation process. Frozen sectioning is quicker, although these samples are of lesser quality than the chemical fixation samples. Typically, frozen section is used to determine the borders, or edges, of a tumor while surgery is being performed.
In both processes, the tissue is often stained using pigments to help the pathologist identify the structure of the cells and pinpoint any abnormalities. With the improvement in recent technology, digital imaging is being used to aid in the scrutiny of tissue samples from surgeries, biopsies, and even autopsies to help find out the cause of death. Histopathology examinations can also help determine the cause of several health problems besides cancer, including pregnancy issues, by examining tissue from the placenta or the reaction of tissues to certain medications.
In the treatment of cancer, a histopathology examination of the tissue removed for biopsy or from surgery is very important in planning the proper course of treatment. The pathologist prepares the sample sent during surgery to examine and advise the surgeon whether or not to proceed or to inform the surgeon when the borders are clear. In a biopsy, the pathologist will determine what kind of cells are involved and their stage, which helps in deciding which course of treatment is best for the cancer identified.
Doctors specializing in histopathology have a long educational route. In addition to a college degree in a chosen scientific discipline, a pathologist also needs to complete a four-year doctorate degree followed by three to eight years in residency. He is required to continue his education over the course of his career.