Role and Applications of Diagnostic Cytology - An Overview.

Introduction:

Cytology or cytopathology is a diagnostic test using body fluid or tissue to examine the cells.

Cytology examines cells from body tissue and fluid to reach a diagnosis. These cells are viewed under a microscope to determine any changes or abnormalities in the cells. Examination of cells requires a small tissue sample.

What Are the Types of Cytology?

There are two types of cytology; exfoliative cytology and interventional cytology.

• Exfoliative Cytology: It involves examining cells shed by the body or scraped from the body tissue.

• Interventional Cytology: It involves intervention in the body and invasion of the skin for the collection of samples.

What Is Exfoliative Cytology?

Manual tissue scraping is done in the following type of cytology:

• Gynecological cytology involves scraping off cells from the cervix with a swab. This technique is termed a pap smear.

• During endoscopy, gastrointestinal cytology involves scraping off cells from gastrointestinal organs like the stomach and esophagus.

• Skin and mucous cytology involve scraping off cells from mucous membranes of the nose and mouth.

• Respiratory cytology, like spit and mucus from the cough, helps diagnose respiratory ailments.

• Urinary cytology involves the collection of urine for cytological examination.

• Discharge cytology includes any abnormal discharge from any body part. This discharge can be vaginal, ear, or eye related.

What Is Intervention Cytology?

Interventional cytology involves intervention in the body and invasion of the skin for the collection of samples. Fine needle aspiration is a common type of interventional cytology. A thin needle is injected into the area of concern to obtain the sample. Fluid is drawn out and examined for the cells under the microscope. This fine needle aspiration can be done for the following conditions:

• Nodules or masses (solid lumps in the body).

• Cysts (fluid-filled sacs in the body).

• Lymph nodes.

• Pleural fluid (obtained from the lung and chest wall area).

• Pericardial fluid (the fluid present around the heart).

What Are the Uses of Cytology?

Physicians and pathologists use cytology for diagnosis. Cytopathology is carried out if a patient shows certain signs and symptoms that need diagnostic tests.

• It can help accurately classify the disease from the list of differential diagnoses.

• Screening tests can be performed using cytology to detect the disease even before the appearance of the symptoms. A pap smear is a type of screening cytology.

• Cytology helps in the diagnosis of infectious diseases, inflammatory diseases, and thyroid diseases.

What Is the Process of a Cytology Test?

Each cytology test is different depending on the type of cells examined. These tests are simple and painless. The patient is well explained about the prerequisites for the test. The variety of samples also makes a difference; samples can be tissue or fluid. The healthcare personnel who performs the cytology test sends the tissue sample cells to a laboratory, and then a cytologist or pathologist examines the cells under a microscope, detecting abnormal cells with specific characteristics. The pathologist further sends a report of the findings to the physician for the results. Cytology can be carried out as follows:

• Collection of the Cells: Cells are collected from the part of the tissue that needs to be examined. Cells can be collected by brushing or scraping the surface or body part. Depending on the need, sample collection can be done by a physician, gynecologist, pulmonologist, or lab technician. Collection of fluid or discharge from the body, like urine or sputum. Fine-needle aspiration can be used to collect fluid from an affected area of the body.

• Processing of the Cells: The samples mentioned above, once obtained, are spread on a glass slide. This assembly is called a smear. These smears are sent to the pathological lab for further examination. If the sample involves body fluids, making smears is impossible. Then the fluid samples are labeled and shipped in small containers for analysis. Depending on the type of smear, these smears are treated with different stains. Stains are the colored dyes that the cells take up. These colored cells are then examined under the microscope. The stains make the cells easier to visualize and examine under a microscope.

If the cytology sample is a fluid, a centrifuge is used to separate the cells to be examined. A centrifuge mixes the sample at high speed to obtain the cells. These cells are put on the glass slide to form a smear, followed by staining.

• Examination of the Cells: Once the smear is prepared and stained, these smears are examined under a microscope to evaluate any abnormal cells. These abnormal cells are made with a spot of special ink for identification. This process is followed by analysis and diagnosis.

• Results: The examination results are put together and sent to the respective provider of the sample. A report for a cytology test includes the following features:

• Presence or absence of abnormal cells.

• Type of disease, infection, or cancer suggested by abnormal cells.

• The cells that can help grade the stage of cancer.

• While identifying the type of cancer cell in the sample, close differentiation from the cells in the surrounding.

• If a biopsy of the tissue is needed in the future.

The time taken for the test results depends on the factors given below:

• The type of tissue cells.

• Whether it is needed to observe more tissue or cells.

• The use of special stains.

• Second opinion requirement.

• Processing time.

What Are the Advantages and Disadvantages of Cytology Tests?

• Advantages:

Less invasive.

Less discomfort and pain.

Low risk of complications.

Low cost.

• Disadvantages:

False negative or false positive result.

Need for biopsy in the future.

What Is the Difference Between Cytology, Histology, and Biopsy?

Cytology (cytopathology) is a subspeciality of pathology. Histology involves an examination of an entire tissue, which contains different types of cells. Cytology tests and biopsies determine a diagnosis. Cytology is the examination of cells. A tiny sample is needed to examine under a microscope, making the procedure painless. Biopsies involve larger tissue sections, making the procedure more invasive than cytology. There might be a need for anesthesia.

Conclusion :

Cytology tests are a widespread and painless way to diagnose and screen diseases. Cytopathologists need to be prepared to use this evolving technology in a world where we need to do more with less. Cytology can be a great diagnostic tool.