Cytopathology

Cytopathology (from Greek κύτος, kytos, "a hollow"^[1]; πάθος, pathos, "fate, harm"; and -λογία, -logia) is a branch of pathology that studies and diagnoses diseases on the cellular level. The discipline was founded by Rudolf Virchow in 1858. A common application of cytopathology is the Pap smear, used as a screening tool, to detect precancerous cervical lesions and prevent cervical cancer.

Cytopathology is frequently, less precisely, called cytology, which means "the study of cells."^[2]

Cell collection

Two methods of collecting cells for analysis are:

1. Exfoliative Cytology – Cells are extracted from fluid shed into the body cavities. For example, in pleural fluid, ascitic fluid, or in the case of the Pap smear, cells scraped from the cervix.
2. Fine Needle Aspiration Cytology or Needle aspiration biopsy – A needle attached to a syringe is used to aspirate (pull out) cells from lesions or masses in various organs of the body by either free drainage or application of negative pressure (suction). FNAC can be done directly on a mass in superficial regions like the neck, thyroid or breast; or it may be assisted by ultrasound or CAT scan. The technique is widely used in many countries. Being a skill dependent procedure, the success rate may vary. If performed by a pathologist alone, or as team with pathologist-cytotechnologist, the success rate of proper diagnosis is superior than when performed by a non-pathologist^[3].

Equipment

Fine needles are 23 to 27 gauge. Sometime a syringe holder may be used to facillitate using one hand to perform the biopsy while the other hand is immobilizing the mass. Imaging equipment such as a CT scanner or ultrasound may be used to assist in locating the region to be biopsied.

Parameters

The nucleus of the cell is very important in evaluating the cellular sample. In cancerous cells, altered DNA activity can be seen as a physical change in the nuclear qualities. Since more DNA is unfolded and being expressed , the nucleus will be darker and less uniform, larger than in normal cells, and often show a bight red nucleolus.

While the cytologist's primary responsibility is to discern whenther cancerous or precancerous pathology is present in the celluar sample analysed, other pathologies may be seen such as:

• microbial infections: parasitic, viral, and/or bacterial
• reactive changes
• immune reactions
• cell aging
• amyloidosis
• autoimmune diseases

Various normal functions of cell growth, metabolism, and division can fail or work in abnormal ways and lead to diseases.

Cytopathology is best used as one of three tools, the second and third being the physical exam and medical imaging. Cytology can be used to diagnose a condition and spare a patient from surgery to ontain a larger specimen. An example is thyroid FNA, many benign conditions can be diagnosed with a superficial biopsy and the patient can go back to normal activities right away. If a malignant condition is diagnosed, the patient may be able to start radiation/chemotherapy, or may need to have surgery to remove and/or stage the cancer.

Some tumors may be difficult to biopsy, such as sarcomas. Other rare tumors my be dangerous to biopsy, such as pheochromocytoma. In general, a fine needle aspiration can be done anywhere it is safe to put a needle, including liver, lung, kidney, and superficial masses.

Many clinicians are not trained to perform fine needle aspiration biopsies properly, and then when they do not obtain diagnostic material, believe that cytology is not useful. Proper technique takes time to master. Cytotechnologists and cytopathologists can assist clinicians by going to procedures and assisting with collection techniques. A "quick read" is a peak under the microscope and can tell the clinician if they have obtained enough diagnostic material. Cytological specimens also need to be properly prepared so that the cells are not damaged.

Sometimes more information about the specimen is helpful. Immunohistochemical stains and molecular testing can be performed, especially if the sample is prepared using liquid based cytology. Often "reflex" testing is performed, such as HPV testing on an abnormal pap test or flow cytometry on a lymphoma specimen.

Body regions

Cytopathologic techniques are used in the examination of virtually all body organs and tissues:

• Gynaecologic cytology - concerning the female reproductive tract
• Urinary tract cytology - concerning the ureters, urinary bladder and urethra
• Effusion cytology - concerning fluids collections, especially within the peritoneum, pleura and pericardium
• Breast cytology - principally concerning the female breast
• Thyroid cytology - concerning the thyroid gland
• Lymph node cytology - concerning lymph nodes
• Respiratory cytology - concerning the lungs and airways
• Gastrointestinal cytology - concerning the alimentary tract
• Soft tissue, bone and skin cytology
• Kidney and adrenal cytology
• Liver and pancreas cytology
• Central nervous system cytology
• Eye cytology
• Salivary gland cytology

See also

• American Society of Cytopathology
• Cell biology

References

External links

• CYTOPATHNET Online Resource Center for Cytopathology
• American Society of Cytopathology
• bushy six-page mindmap PDF expanding injury, death, aging, stress adaptation, and amyloidosis.
• Med/Utah

This article related to pathology is a stub. You can help Wikipedia by expanding it. v • d • e