How Cytopathology Works

Cytopathology is the study of disease at the cellular level. "Cyto" refers to cell and "pathology" to disease. Cytology tests look at cells, which are usually obtained from fluid samples, scrapings, or brushings. These tests are used to examine single cells or small clusters of cells and to assess whether they are normal or show signs of disease.

Cytopathology and cytology both refer to the study of cells, and they are often used loosely to convey the same thing. Cytopathology and cytology reports describe findings that help determine whether or not the examined cells are diseased or normal.

Cytology can be done as a screening test or a diagnostic test. For example, the Pap smear is a cytology test used to screen for abnormal cells on the cervix, even when there is no sign of disease.

This type of test is useful when there may not be any outward symptoms of illness and the cells are relatively easy to sample. Cytology can also be done to assist in the diagnosis when there is a known or suspected a disorder, such as when a fine needle aspiration is used to sample cells from a tumor.

Cells examined for cytopathology can come from fluids such as urine or sputum or may be extracted from tissue, such as from inside the chest or abdomen. Cells can also be extracted by inserting needles into growths or diseased areas or tissues—called fine-needle aspiration cytology, or FNAC.

The cells are concentrated, plated and stained on slides and examined under the microscope. FNAC is a common test used to identify lymphoma with samples taken from lymph nodes or other body tissues. However, the initial diagnosis of lymphoma usually requires a larger sample from a biopsy.

A pathology department in a hospital is set up to do different kinds of tests on worrisome 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 cells are examined along with “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. This is sometimes referred to as "histological architecture," which can be important in the evaluation of the appearance of conditions such as lymphoma.

Also known as: Cytology report, cytopath

Related terms:

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