How Cytopathology Works

Cytopathology and cytology are diagnostic processes by which the cells obtained from biopsy, fluid samples, scrapings, or brushings are specially prepared and examined with a microscope. 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 reports describe findings that help determine whether or not the examined cells have characteristics of illnesses, like infection, inflammation, or cancer.

Cytopathology is the study of disease at the cellular level. "Cyto" refers to cell and "pathology" to disease.

Uses

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 disorder, such as when a fine needle aspiration is used to sample cells from a tumor.

Process

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—such as with a fine-needle aspiration cytology (FNAC) procedure.

The cells are concentrated, plated, and stained on slides so they can be examined under the microscope. FNAC is a common test used to identify the spread of 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.

Cytopathology vs. Histopathology

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

Some aspects of a disease can be inferred based on the characteristics of individual cells—including the appearance of the nucleus, the presence of cellular proteins, and the cell’s morphology (shape).

Other aspects of disease stand out only when the cells are examined along with other nearby 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 extends the analysis so that pathologists can see abnormalities related to attachments between cells, and explore whether the cell appears normal given its location within the tissue. This is sometimes referred to as "histological architecture," which can be important in the evaluation of the appearance of conditions such as cancer.

Also known as: Cytology report, cytopath

Related terms:

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