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This overview is intended to give a general outline about the basics of Cytopathology. This is a field that is gaining tremendous momentum all over the world due to its speed, accuracy and cost effectiveness. This review will include a brief description about the history of cytology from its inception followed by recent developments. Discussion about the different types of specimens, whether exfoliative or aspiration will be presented with explanation of its rule as a screening and diagnostic test. A brief description of the indications, utilization, sensitivity, specificity, cost effectiveness, speed and accuracy will be carried out. The role that cytopathology plays in early detection of cancer will be emphasized. The ability to provide all types of ancillary studies necessary to make specific diagnosis that will dictate treatment protocols will be demonstrated. A brief description of the general rules of cytomorphology differentiating benign from malignant will be presented. Emphasis on communication between clinicians and pathologist will be underscored. The limitations and potential problems in the form of false positive and false negative will be briefly discussed. Few representative examples will be shown. A brief description of the different techniques in performing fine needle aspirations will be presented. General recommendation for the safest methods and hints to enhance the sensitivity of different sample procurement will be given. It is hoped that this review will benefit all practicing clinicians that may face certain diagnostic challenges requiring the use of cytological material.
The art and science of cytology and cytopathology has been implemented and recognized as early as the 18th and 19th centuries.[1–5] However the progress and the standardization of this branch of pathology were not founded completely until the late years of the 20th century. The first American Board of Examination in cytopathology was undertaken in 1989. Europeans, especially north Scandinavian countries, were able to utilize this technique even before the World War II.[1,4] The science of cytopathology is currently well standardized with two major branches, exfoliative and aspiration biopsy.
George Papanicolaou, after whom the famous Papanicolaou (Pap) smear and Pap stain was named, was one of the initial pioneers who drove the attention to the science of the ability to make a diagnosis looking at slides with a smear of cells in the period between 1917 and 1928. The initial North American scientific papers describing tumor diagnosis by cytological examination was published in 1930 from New York Memorial Hospital by Drs. Martin and Ellis followed by a publication by Dr. Stewart in 1933.[6,7] After this the scientific and the medical community started paying attention and aggressively pursuing this sub specialized field of pathology.
The first examination of American Board of Cytopathology was held in 1989 after standardization of this branch of pathology. Currently, one-year fellowship of Cytopathology in an accredited program is needed to be eligible for this exam. In addition, the Accreditation Council for Graduate Medical Education (ACGME), the agency that accredits residency training programs in pathology in the United States of America (USA) currently mandated documentation of fine needle aspiration (FNA) performance training for both residents and cytopathology fellows.
Although there are still few limitations for making the initial diagnosis merely on the basis of cytological material, these limitations are shrinking day by day and the role that cytopathology play as an initial diagnostic tool is currently a standard procedure.[10–16]
The difference between surgical biopsy and cytopathology material, including fine needle aspiration biopsy is shown in the Table 1. Now, it is well recognized that using cytology including FNA is cost effective, simple, accurate and a safe procedure for making a specific diagnosis that dictates management decisions by the treating clinicians.[17–26]
This objective is the ultimate goal. Clinicians, patients, and pathologists are all interested to reach a definitive specific diagnosis utilizing single diagnostic test. It is well recognized now that the utilization of different cytological examinations from different organs provides sufficient diagnostic information that drives treatment decisions.[27–38]
The success story of utilizing Papanicolaou smears in detecting early precursor lesions of cervical cancer is well known in the developed word. Rates of cancer death due to cervical cancer dropped tremendously after the 1960s when the Papanicolaou smears screening programs had started.[39–43]
Cytological examinations of specimens taken from different sites as a follow-up after establishing the initial diagnosis is a routine procedure. Sputum, bronchoalveolar lavage, and bronchial brushings are frequent samples that are used as follow-up for patients with a previous diagnosis of pulmonary carcinoma. Additional common samples that can be used include: pleural fluid, peritoneal fluid, discharge samples, cerebrospinal fluid, and FNA from any palpable or non-palpable deep-seated new lesions that appear during the follow-up period.
This is usually achieved as part of staging or using the cytological samples to perform ancillary studies, such as Her-2Neu analysis on breast mass aspirates.
The advantages of utilizing cytological examination over traditional tissue are well known, the most important of which are:
The procedures that are used to get cytological samples are extremely safe. Complications are very rare and when they occur they are relatively mild. Hematomas and pneumothoraces are among those. The most serious complication that may occur and had been reported is the development of pneumothorax during FNA of lung lesions. However, less than 5% of those are serious and require insertion of chest tube.[44–47] In addition, if the procedure is done under image guidance, immediate evacuation using the same needle is now recommended and had been successfully achieved. Paying attention to the risk factors for the development of pneumothorax may decrease their rate. Hematomas are observed more frequently in patients who have coagulopathies.[48–51] Prevention of such complications is easily achieved by applying gentle pressure for longer periods after the procedure. It is also recommended to consult with the hematologist in the institution to prepare those patients who suffer from bleeding disorders or are on anticoagulation therapy. Pain and patient discomfort are relatively mild and can be prevented by appropriate preparation of patients and by applying local anesthesia, if necessary. Infections are extremely rare and can be avoided by following the international safety guidelines and sterile techniques.[52–54]
It is well known that getting most cytological samples is simple. With increasing familiarity of different sampling techniques, currently almost all institutions and health care providers are aware of the technology and it is part of routine investigative and diagnostic patient work up. Description of different types of samples will follow.
The most important principle is to have a simple clear communication between pathologists and clinicians with the basic understanding of teamwork. In addition, using a common clear language of communication is absolutely critical to avoid mismanagement. This includes a clear understanding of the terminology, which is used in the cytopathology final report. It is always desirable to communicate with clinicians at any time. Pathologists who are trained and familiar with cytopathology are obliged to establish bridges of communications with radiologists and clinicians. This can be achieved by one on one personal contact or through tumor board settings and clinicopathological correlation conferences. This, in many times, will have a positive impact in patient care since a diagnosis based on cytological examination will not be made in vacuum. The technical aspects of establishing a cytology and aspiration services are described below.
The samples represent cells that exfoliate from superficial or deep serosal or mucosal surfaces. This includes:
Different names are used to describe this expanding technique. The most famous ones are FNA, fine needle aspiration biopsy (FNAB), and needle aspiration biopsy cytology (NABC). All of them mean the same thing; aspirating cellular material using a fine needle to make a diagnosis. This technique has been used from any lesion in the body which includes two major areas:
The initial smears are usually stained by a quick stain (stains, which needs approximately one minute to perform) such as Diff Quick (DQ) stain, a modified Romanowsky stain. This type of stain is done on slides with material after air-drying and this is why they are also called air-dried based stains. The other set of slides are fixed in basic ethanol-based solution (preferable 95% ethanol) for different type of stain, the Papanicolaou stain. In addition to the previous smears which are prepared at the time of the fine needle aspiration, the rest of the material is usually flushed in a ethanol or formalin-based solution after which the material is centrifuged and a small mini biopsy is created from the concentrated cellular material at the bottom of the tube; this is known as the cell block. The slides from the cell block are usually stained by a regular Hematoxylin and Eosin (HandE) stain. These three types of stains are commonly used in different laboratories. Each one of those has its advantages and disadvantages. For example, DQ stain is good for microorganisms, cytoplasm, and background material staining. In the meantime, Papanicolaou stain is more superior for demonstrating the nuclear details, which are the most important and specific in making the diagnosis of malignancy. The HandE stain combines the advantages of both Papanicolaou and DQ stains and gives the pathologist a chance to evaluate tissue-like stains similar to routine biopsies.
Different types of smear preparations are utilized in the cytopathology laboratory, which includes:
There is still no agreed upon standard for the best aspiration technique in cytopathology. However, all FNA experts agree on one thing, every aspirator have to get comfortable with one method and modify it as more experience is gained. The bottom line is to get enough diagnostic cells from the area of interest. The gauges of the needles used vary, however, 21-25 French gauge needles are the most frequent. Whether to use a gun (syringe holder) or not when negative pressure is utilized, is left for the level of comfort of the aspirator. Some believe that using the gun provides more control and more cells. The most common techniques [Figures [Figures55 and and6]6] that are used include:
Basically all ancillary studies can be done using cellular material obtained either from exfoliative or FNA technique. These include:
To have an informative final cytopathology report after doing the procedure and making the appropriate studies to make a specific diagnosis, it is very important that it expresses few important components.
It is recommended that a statement describing if the material was adequate to make an interpretation is inserted in the final report. This becomes critical if the material is inadequate and the final message is to re-evaluate and/or re-investigate. As mentioned before, the presence of a pathologist or performance of the procedure by a pathologist is highly recommended in order to increase the adequacy rate.
A specific diagnosis is always desired when possible. Sometimes the diagnosis is broad, such as “positive for malignant cells” and then this will be followed by descriptive diagnosis and a comment entailing a differential diagnosis to help the clinicians. In some cases, not all the diagnostic criteria are present or the atypical cells are very few; in these circumstances a “suspicious for malignancy” diagnostic category can be used. This has to be interpreted so that a second diagnostic approach is necessary.
Sometimes descriptive diagnosis and microscopic description of the smears may be helpful for the clinicians to make a therapeutic decision. For example, if a nipple discharge was submitted on two smears from the clinician's office and sent to pathology department and those smears contained numerous macrophages but no mammary epithelial cells are seen for evaluation. Although no epithelial cells are present in this case, the features are most likely consistent with a benign process since the increased number of macrophages and the lack of epithelial cells. In this circumstance, writing a simple microscopic descriptive diagnosis is of a great help to the clinician.
In certain circumstances a comment is needed to clarify or add some information that may harbor clinical importance.
Sometimes we need to call the clinicians and discuss the case with him either face to face or over the telephone.
The presence of a pathologist/cytopathologist at the time obtaining material, especially in fine needle aspiration biopsy procedures, is highly recommended and saves a lot of effort and money in making one procedure diagnostic and cost effective. However, sometimes the material is non-diagnostic or acellular, and this should be conveyed in the final cytopathology report. So careful reading of the final cytopathology report is mandatory so that no misunderstanding or miscommunication can occur. Sometimes the material is sub optimal due to multiple factors, the most frequent are:
There is no single feature that is diagnostic of malignancy. It is the constellation of multiple factors that vary depending on the tissue aspirated, the collection technique and the smear preparation method. It is very important to be aware of these variables before attempting to make a final cytological diagnosis. The general features of malignancy in cytological slides are high cellularity, cellular enlargement, increased nuclear/cytoplasmic ratio, nuclear hyperchromasia, discohesiveness of cells, prominent and large nucleoli, abnormal distribution of nuclear chromatin, increased mitotic activity and specially the presence of abnormal ones, nuclear membrane abnormalities, cellular and nuclear pleomorphism, and background tumor necrosis (also known as tumor diathesis). Ultimately, we are all responsible for providing an accurate cytological diagnosis.
Problems can arise anytime anywhere from the time the patient is seen until the time the final report is transcribed and faxed or sent to the clinician. Trouble shooting is very important to identify problems, which can arise anytime.
On the other hand, false positive diagnosis is usually caused by:
Each organ has its own diagnostic limitation by cytology. However, common examples are provided in this list:
Utilizing the science of cytopathology whether exfoliative or FNA is cost effective, fast, simple and accurate. With the recent improvements in technical aspects and the appearance of cell block technique in cytopathology, the old gold standard of “must have tissue to make an accurate diagnosis” is rapidly changing.
Team work emphasizing excellent communication skills is very important between pathologists and clinicians.
All the information about the patient should be given to the pathologist in order to decrease the frequency of pitfalls that were described.
Encouragement of clinical pathologic correlation conferences and tumor boards is very helpful to establish common language and protocols with appropriate guidelines for diagnostic utilization of cytology materials.
Source of Support: Nil
Conflict of Interest: None declared.