Simple intra-oral soft tissue biopsy is a common surgical procedure which can be performed by both general dental practitioners and dental specialists. It is crucial that all dental practitioners who perform biopsy procedures have a thorough knowledge of oral anatomy, oral pathology and oral surgery. Performing a clinical extraoral and intraoral soft tissue examination is an essential part of the initial assessment of a patient and often leads to the recognition of an oral pathologic lesion by a dental practitioner.1
Simple intra-oral soft tissue biopsy procedures are most often performed using local anesthetics. The use of adjunctive sedation techniques, including Nitrous Oxide and/or IV sedation, is based on patient assessment, patient request and often times, the location of the lesion. A dental practitioner must have a thorough understanding of regional anatomy and possess good surgical skills, prior to attempting an intra-oral soft tissue biopsy procedure.1 In the case of lesions close to major anatomical structures and/or more proximally located lesions, the patient should be referred to an oral surgeon.
The patient should initially be informed of the clinical findings and should be provided with a provisional diagnosis of the lesion. All of the potential risks and complications, including pain, swelling, bleeding, bruising, wound infection, nerve injury and sinus involvement associated with surgical intervention must be discussed with the patient pre-operatively. A verbal and written informed consent should be obtained prior to the surgical procedure.
Simple intra-oral soft tissue biopsies can be divided into two categories: incisional and excisional biopsy procedures.2,4 An incisional biopsy is performed on larger lesions and those lesions requiring a definitive diagnosis prior to final treatment, which could involve either surgical or non-surgical therapy (e.g. radiation or chemotherapy). These lesions generally measure more than 1 cm and may be more aggressive in nature. Excisional biopsies are generally performed on smaller lesions measuring less than 1 cm and are located in easily accessible regions of the oral cavity.
Prior to performing any surgical procedure, the clinician should be fully aware of the patients’ medical status. This involves a thorough review of their medical and dental history, including previous surgeries, medications, allergies and any social behaviors such as smoking, alcohol or illicit drug use. Next, the clinician must perform a thorough clinical and radiographic examination.1
Administration of local anesthesia for a biopsy procedure can be performed either locally, with infiltration near the lesion, or regionally, with a nerve block technique. It is important, however, to avoid injecting local anesthetic directly into a lesion or superficially around or under the lesion.3 This will cause distortion of the lesion and its margins and prevent accurate diagnosis by the oral pathologist.
Once local anesthesia has been obtained in the region of the lesion to be biopsied, the clinician should firmly retract the soft tissues to create tension and allow for accurate incision margins. An elliptical incision should be made around the lesion with a minimum of a 1 mm margin (for excisional biopsies). Once the initial apex of the ellipse is created, the clinician should gently elevate the soft tissues of the biopsy specimen using a non-toothed tissue forceps. The incision should then be carried deeper below the lowest margin of the lesion, angling the incision towards the center from the incision margins. It is important to avoid using a high-vacuum suction or wide diameter suction tip during the surgery so as to avoid inadvertent suctioning and loss of the specimen. It is recommended that the surgical assistant intermittently blot the surgical site using a sterile 2 x 2 gauze or sterile sponge.
When performing incisional biopsies on larger lesions the technique is different and requires the clinician to cut into the lesion. These types of biopsies are more complex and should be referred to a specialist.
Once the lesion is freed from the remaining soft tissues, it should be immediately placed into a sterile pathology specimen jar containing buffered 10% formalin for fixation2. Prompt fixation is needed to avoid autolysis (breakdown of cell and tissue structures) which will make histological examination difficult or impossible. It is advisable to have ready a specimen container with the proper fixative before taking a biopsy.3 Specimen containers with buffered 10% formalin are available from pathology laboratories. The container must be labelled with patient information, such as name, birthdate, date and site of biopsy.
Firm manual pressure must initially be applied to the surgical site to assist in hemostasis. The use of electrocautery or a nitrogen stick may be utilized by those clinicians who are familiar with their use and as an adjunct to the manual pressure technique. Finally, the incision should be closed in a primary fashion using either resorbable or non-resorbable sutures in an interrupted suture pattern. The final incision should appear as a straight line with even leveled margins.1 Sterile gauze should again be applied to the surgical site to assist with hemostasis and prevent swallowing of blood by the patient. In general, a healthy patient with no bleeding disorders or not taking medications which interfere with clot formation or coagulation will form a blood clot within 30 minutes of the procedure. Slight oozing of blood from the surgical site is normal and may continue for the first 24 hours after the biopsy procedure. As a result, the patient should be provided with a packet of gauze to change out every 20 to 30 minutes over the course of the day. The gauze must not be kept in the mouth overnight. It is important to provide the patient with verbal and written post-operative instructions.
The specimen and appropriate accompanying documentation must then be sent to the pathology laboratory in a timely fashion for analysis and diagnosis.
Processing and Analysis in the Pathology Laboratory
The specimen bottle and requisition should be labeled with the patient’s full name and date of birth, the name and address of the clinician and date of biopsy. Additional information on the biopsy specimen, such as the site of the biopsy, clinical history and radiographic findings should also be provided on the requisition2.
Upon receipt in the pathology laboratory, the specimen is registered in the laboratory database. The gross appearance is recorded and the specimen is measured. Large specimens are divided and the specimen is submitted in a plastic cassette that goes into an automated histologic processor. This is typically an overnight process, in which the specimen is brought through a series of alcohols of increasing strength to extract the water content. The dehydrated specimen is put into xylenes to clear the alcohol, in preparation for embedding. On day 2 in the lab, the specimen is embedded in paraffin wax, which allows thin (4 – 5 microns) sections to be cut by a microtome onto glass slides and stained with histologic stains, usually H & E, or hematoxylin and eosin. On day 3 (approximately 48 hours after the specimen arrived in the lab), slides are read by a pathologist and a report is generated. Urgent reports are verbally transmitted to the clinician by telephone and also faxed upon request, while routine reports are sent in the mail. The timeline and protocol described above are used by the oral pathology laboratory at the Faculty of Dentistry, University of Toronto. Other laboratories may follow different routines depending on their workflow and organization.
Discussion of the Pathology Report with the Patient
The patient should be scheduled for a follow-up appointment in 7 to 10 days for re-assessment of the surgical wound and for discussion of the diagnosis. Further intervention, including referral to a specialist, may be required based on the biopsy results. In the case of a complete excision of a benign lesion, the patient should be seen for routine follow-up during the healing period and the site should be evaluated on recall visits to the clinician’s office.
It is also good practice to send a copy of the biopsy report to the patients’ physician and other health care professionals whom the patient is seeing routinely.
Common Problems and Errors
One of the most common problems associated with intra-oral soft tissue biopsy procedures is improper handling of the specimen. The use of excessive force while grasping the specimen or the improper placement of the surgical incision can lead to poor tissue quality for pathologic assessment. Improper use of laser or electrocautery will cause a heat-induced artifact that obscures cellular detail2.
Another common problem is inadequate size of the specimen for pathologic evaluation, or a specimen that is unrepresentative of the lesion3. Pre-operative assessment and planning of the surgery by the clinician and appropriate surgical technique will help prevent these issues. The clinician should also have a sound knowledge of the lesion that is being investigated and the anatomy of the area from which the biopsy is taken.
Inadequate fixation of the tissue sample will lead to failure of histological diagnosis. The tissue should be completely immersed in at least 10 times its volume of fixative promptly after removal from the patient3. In case a biopsy is already taken and buffered 10% formalin is not available, 70% ethanol may be used to preserve the tissue temporarily until it arrives at the pathology lab when it is then transferred to formalin. Sterile water or saline should not be used as these liquids do not have any preservative ability. The specimen in fixative should not be allowed to freeze, which is a particular consideration if the specimen is left in an outside mailbox in winter.
One exception to immediate fixation is the mucosal specimen for direct immunofluorescence study to detect antibody deposits, for example in vesiculobullous diseases such as pemphigus vulgaris. In this situation, the tissue should not be fixed but placed into Michel’s transport medium and transported to the laboratory within a few hours5. Specimen bottles with Michel’s transport medium are available from laboratories that provide this analysis. The medium has a more limited shelf life than formalin, and should be obtained fresh when planning these biopsies.
Hupp JR, Ellis E III, Tucker MR. Contemporary Oral and Maxillofacial Surgery, 5th ed. St. Louis: Mosby, 2008.
Melrose RJ, Handlers JP, Kerpel S, Summerlin D and Tomich CJ. The use of biopsy in dental practice. General Dentistry 2007:457-461.
Cawson RA and Odell EW. Essentials of Oral Pathology and Oral Medicine, 6th ed. Edinburgh, London, New York: Churchill Livingstone, 1998:6-9.
Rosai J. Surgical Pathology, 9th ed. Edinburgh, London, New York: Mosby, 2004:8-9.
Fischer EG. To fix or not to fix: Michel’s is the solution. Int. J. Surg. Pathol. 2006;14:108.