Oral Exfoliative Cytology

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Welcome to the Continuing Education course on oral exfoliative cytology that was developed by the Department of Oral Pathology at the Medical College of Virginia/Virginia Commonwealth University School of Dentistry and is offered over the Internet. This self-instructional course is designed for dentists who are interested in learning more about the diagnostic technique of oral cytology. CE CREDIT: We award 2 hours of CE credit for this course after you submit your answer sheet to us.

The topics to be covered include:

• Background
• Indications
• Contraindications
• Diagnostic accuracy
• Technique
• Cytologic diagnosis
• Summary
• Ordering supplies
• Post-test

Background

Exfoliative cytology is the histopathologic examination of cells that have been obtained by their physical removal, followed by their placement on a glass slide, and then appropriately stained. The term "Pap smear" is commonly used for exfoliative cytology, but it only refers to the method of staining and is in honor of the man who is credited with developing the staining technique, Dr. Papanicolaou.

The first modern use of cytology for head and neck cancers was in 1949 when Morrison and his colleagues successfully used exfoliative smears for nasopharyngeal cancers. In 1963, the American Dental Association's House of Delegates passed resolutions that acclaimed oral cytology as an "excellent measure in prolonging life" and endorsed training for dentists in cytologic technique. In a 1967 editorial in the Journal of the American Dental Association, it was recommended that "Oral cytology should be a part of every oral examination in which the dentist detects even the least suspicious lesion". Given that these recommendations were published approximately 30 years ago, it is surprising that only 9.2% of the dentists in Virginia have ever done an oral cytologic smear. One explanation is that most of the dentists in Virginia (58.3%) were never taught how to do a smear and would naturally be hesitant to do one in private practice. Also, there is a lack of the necessary materials in 96.9% of the dental offices.

There has been a reduction in the number of cervical cancer deaths from 8,487 in 1960 to 4,800 in 1997 in the United States and most experts feel that this decline is due to the widespread use of the cervical Pap smear. However, what is sometimes overlooked is that oral cancer is twice as prevalent as cervical cancer and that it now causes almost twice as many deaths per year.

Comparison of Oral Cancer to Cervical Cancer in the United States

	Oral	Cervix
Number of deaths, 1960	6,175	8,487
Estimated number of deaths, 1997	8,440	4,800
Estimated new cases, 1997	30,750	14,500

Given the similarity in mucosal pathology between the oral cavity and the cervix, is it possible that the use of cytology in dentistry could also reduce the number of oral cancers?

Indications

The following are indications for the use of oral cytologic smears:

• A mucosal lesion that appears clinically innocuous and otherwise would not be biopsied.
• Evaluation of an extensive mucosal lesion when it is not possible to do a sufficient number of incisional biopsies for adequate sampling.
• Follow-up for patients with a prior diagnosis of either a premalignant or malignant mucosal lesion.
• If the patient's medical status is too fragile for a surgical biopsy or if the patient refuses.
• To assess potential oral candidiasis and viral infections.

Cytology should be considered for any lesion of the surface of the oral mucosa if the diagnosis can not be established by clinical exam or history. The cytologic smear is an adjunct and can not be considered the definitive diagnosis.

Contraindications

There are no known contraindications to oral exfoliative cytology.

Diagnostic accuracy in diagnosing oral cancer

A review of 14 different studies found that cytologic smears correctly identified 1,141 of 1,306 (87.4%) biopsy-proven squamous cell carcinomas of the oral cavity. Another important factor is how many benign lesions are incorrectly diagnosed as either suspicious or malignant by a smear. Seven studies evaluated 16,422 patients with biopsy-proven benign oral lesions who had cytologic smears done before the biopsy and found that 141 (0.9%) of the smears were signed out as suspicious.

Therefore, if we combine this data, cytologic smears correctly identified about 90% of all oral cancers and incorrectly suggested malignancy in about 1% of benign lesions. There is limited information available on the accuracy of histopathologic diagnoses based upon surgical biopsies, but one group showed that 2.5% of oral cancers were not correctly diagnosed on the initial biopsy. There are also anecdotal reports of patients in whom the initial biopsy was negative but the initial smear was suspicious, and subsequent biopsies confirmed the presence of carcinoma.

The accuracy of cytology in correctly diagnosing benign lesions of the oral mucosa is unknown but, based upon our clinical experience, we would anticipate it being low. However, our experience does indicate that cytology is useful in detecting the presence of fungal organisms such as Candida albicans.

Technique

The supplies needed for oral cytology are:

• 2 glass slides
• 1 Cytobrush (if there is more than one lesion, then 1 Cytobrush per lesion)
• Spray-cyte
• Cardboard container and bubble-pack mailer
• A Request for Tissue Examination form

Sequence:

1. Prior to doing the smear, explain to the patient the purpose of the exam and, in general, the steps of the technique.

2. With a pencil, write the patient's name, the date, and the anatomic location of the smear

on the frosted end of a glass slide.

Figure 1Figure 2Figure 3

Do this on two glass slides per lesion because two smears will increase the probability of getting an adequate number of cells.

3. Remove one Cytobrush from the package.

Figure 4 Figure 5

4. Take the top off of the can of Spray-cyte.

Figure 6

5. Put gloves on.

6. With a gauze gently remove any excess saliva in the area that will be smeared.

7. Vigorously scrape and rotate the Cytobrush over the entire lesion.

Figure 7

The scraping should not be painful to the patient but it should be vigorous enough so that it is noticeable and may generate a small amount of bleeding. It is important to rotate the Cytobrush while scraping the lesion so that the exfoliated cells will be on all the bristles.

8. Take the Ctyobrush and spread the harvested cells onto the glass slide by starting at the frosted end and rotating the Cytobrush until you reach the other end of the slide.

Figure 8 Figure 9Figure 10

You should be able to see a white, filmy debris on the glass slide. If the slide appears to be completely clear, then it may mean that there are no cells on the slide.

9. Spray the surface of the glass slide right away with the Spray-cyte while holding the can about 6 inches away from the slide.

Figure 11

The cells will degenerate if they are allowed to air dry. The Spray-cyte contains an alcohol fixative that prevents the cells from degenerating for days to weeks.

10. Repeat the procedure for the second smear on the same lesion.

11. Fill out the Request for Tissue Examination form that includes information about the patient, their medical insurance carrier, location of the lesion, clinical description, and your clinical impression.

Figure 12 Figure 13 Figure 14

12. If there is another lesion(s), you must use a different Cytobrush to prevent crossover of the cells placed on the glass slides. You can use the same Request for Tissue Examination form and indicate that there was more than one lesion.

13. Place the glass slides in the cardboard container, wrap with a rubber band, and place into the bubble-pack mailer along with the Request for Tissue Examination form.

Figure 15 Figure 16 Figure 17

14. Once we have received the slides in our laboratory, it takes about 3-5 working days to process the slides and generate a diagnosis. If there is any urgency, mark on the Request for Tissue Examination form that we should either fax or call the results to your office.

Cytologic diagnosis

A cytologic diagnosis is different than what you might be used to with a surgical biopsy in that we usually just categorize lesions as normal, suspicious, or malignant. Any lesions with either a suspicious or malignant cytologic diagnosis need to be followed with a biopsy of the site. In the case of candidiasis, the diagnosis will indicate the presence or absence of fungal organisms. It is difficult to measure the number of organisms but it is sometimes possible to render a judgement as to whether there were a small or a large number of fungal organisms.

Regardless of the cytologic diagnosis, your clinical judgement is the most factor in determining the care of the patient. If the cytologic diagnosis does not agree with your clinical impression, then you should either repeat the smear or do a biopsy. Keep in mind that the cytologic smear is an aid to diagnosis and does not represent the definitive diagnosis.

Summary

Oral exfoliative Cytology is a diagnostic aid and adjunce to surgical biopsy. The indications for its use include oral mucosal lesions, and follow-up for patients with a history of either a premalignant or malignant lesion. Oral cytology has an accuracy rate of 90% in diagnosing oral cancer. The oral cytologic technize is easy to do and can provide the dentist with help in cases where he or she might be hesitant to perform an invasive procedure, like a biopsy, or desire more information regarding a lesion before referring the patient.

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Last Modified: June 14, 2001
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