What Is Cytopathology?

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.

This article will go over the difference between cytology and cytopathology. It will also explain how histology is different from cytology, and the difference between cytopathology and pathology.

Cytology Uses

A cytology smear is a diagnostic test. A common example is a Pap smear, which 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.

These tests can also be done when there is a known or suspected disorder. An example is doing a fine needle aspiration to collect sample cells from a tumor. When a provider is looking at cells to see if there is a disease, the study is usually called cytopathology rather than cytology.

Cytopathology Process

Cells examined for cytopathology tests can come from body 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.

Cytology vs. Cytopathology

Cytopathology tests are used to examine single cells or small clusters of cells and to assess whether they are normal or show signs of disease. A report from a cytopathology test describes 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 cells and "pathology" to disease. While it shares some terms, cytopathology is different from "cytology," "histology," and "pathology."

Cytology vs. Pathology

Cytology is the study of cells. When cytopathology is used to look at cells for signs of disease, it falls under the umbrella of pathology.

Pathology is a field of medicine that studies diseases. Lab tests, like cytology smears, can be a tool that pathologists use when researching a disease.

Cytopathology vs. Histopathology

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

In cytopathology, 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.

Other terms you might see used in this context are:

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

Summary

Cytology is the study of normal cells. When cells are looked at for abnormalities or signs of disease, it's usually called cytopathology. Pathology is the branch of medicine that looks at why and how diseases happen.

Cytology smears, histology samples, and other cytopathology tests can help pathologists learn about diseases and help providers diagnose them.