How Cytopathology Works

Cytopathology is the study of disease at the cellular level. "Cyto" refers to cell and "pathology" to disease. Cytology tests are done on cells in fluid aspirations, scrapings, or brushings to look at single cells or small clusters of cells and assess whether they are normal or show signs of disease.

Cytopathology and cytology are both words that refer to the study of cells, and they are often used loosely to convey the same thing. A cytopathology report or cytology report describes findings that suggest whether or not cells of interest are diseased or are normal. Disease may or may not be present, so both terms are applicable and in common usage.

Cytology can be done as a screening test or a diagnostic test. For example, the Pap smear is a cytology test done to screen for abnormal cells on the cervix, even though there is no suspicion of disease. This is useful in conditions where there may not be any outward symptoms and the diseased cells are relatively easy to sample. Cytology can also be done to assist in diagnosis if a disorder is suspected, such as when a fine needle aspiration is done on a tumor after it has been discovered.

Cells examined for cytopathology can come from fluids extracted from body cavities—for example, urine, sputum, or fluids—or from sources inside the chest or abdomen. Cells can also be extracted by inserting needles into lumps or diseased areas or tissues—called fine needle aspiration cytology, or FNAC.

These cells are concentrated, plated and stained on slides and examined under the microscope. In lymphomas, FNAC is a common test to identify lymphoma in lymph nodes and other body tissues. However, the initial diagnosis of lymphoma usually requires the larger sample from a biopsy, for a variety of reasons.

A pathology department in a hospital is set up to do different kinds of tests on suspect cells and tissue samples, whether from FNAC or from a larger sample, such as an excisional biopsy.

Some aspects of disease can be readily seen by studying individual cells and their appearance, including the appearance of the nucleus, certain cellular proteins, and the shape or “normal anatomy” of the cell, which is called the cell’s morphology.

Other aspects of disease stand out to the observer only when the suspect cells are seen in the context of “the whole neighborhood” of cells. That’s where histopathology comes in. Histopathology usually refers to whole slices of tissue being viewed and evaluated under the microscope.

While cytopathology relates to abnormalities found within—or expressed by—individual cells, histopathology can extend the analysis into “panorama mode,” if you will, so that pathologists can see abnormalities related to attachments between cells, and explore whether the cell appears normal given its location within the panorama, for instance. This is sometimes referred to as "histological architecture," which can be important in the evaluation of the appearance of lymphoma.

Also known as: Cytology report, cytopath

Related terms:

• Histopathology
• Immunohistochemistry
• Molecular cytopathology
• Cytogenetics
• Molecular diagnostics