Oral Tissue Biopsy Techniques

• Biopsy is the removal of a small tissue sample, fluid, or cells from a living person.
• The removed sample is examined microscopically to diagnose a disease.
• Dental clinicians should know the various biopsy techniques for oral tissues and their specific challenges.
• The aim of any biopsy method is to provide a suitable representative sample for accurate interpretation while minimizing patient discomfort.

Criteria for a Successful Representative Sample

• Representative areas are biopsied in a wedge fashion.
• Include both the lesional tissue and a portion of normal deep tissue.
• Avoid necrotic tissue in the sample.
• A narrow, deep specimen is preferred over a broad, shallow one.
• Reapproximate soft tissue overlying the lesion after irrigation.
• A clinician should sample the most severely and significantly affected tissue.
• Multiple biopsy samples may be needed if the lesion is extensive.

Indications for Biopsy

• Any lesion persisting for more than two weeks without an apparent cause.
• An inflammatory lesion not responding to local treatment after 10-14 days.
• Persistent hyperkeratotic changes in surface tissues.
• Any persistent swelling, visible or palpable, beneath normal tissue.
• Lesions interfere with local function, like fibromas.
• Bone lesions not easily identified by clinical and radiographic findings.
• Unexplained pigmented oral lesions, especially if new or changed.
• Lesion characteristics of malignancy.

Characteristics of Malignancy

• Erythroplasia: A lesion that is totally red or has a speckled red and white appearance.
• Ulceration of lesion.
• Duration: Lesion has persisted for more than 2 weeks.
• Growth rate is rapid.
• Bleeding: Lesion bleeds on gentle manipulation.
• Induration: The lesion and surrounding tissue are firm to the touch.
• Fixation: Lesion feels attached to adjacent structures.

Contraindications for Biopsy

• Normal anatomic and racial variations like physiologic pigmentations, leukoedema, linea alba, tori, and exostosis.
• Compromised general health of the patient, including those on anticoagulant therapy.
• Immediate pre- or post-radiation therapy patients may be predisposed to osteonecrosis if the biopsy exposes bone.
• Benign tumors or those of a vascular nature.
• Very deep lesions with difficult access where the surgical technique is complicated or hazardous due to the risk of damage to neighboring structures.

Types of Biopsy

• Incisional
• Excisional
• Punch
• Aspiration
• Drill

Incisional Biopsy

• A small portion of the lesion is removed, providing a representative tissue sample for diagnostic purposes.

Indications for Incisional Biopsy

• A lesion that has different characteristics at different locations.
• An area under investigation appears difficult to excise due to its large or extensive size (>1 cm in diameter).
• Lesion located in a hazardous location.
• Suspicion of malignancy.

Advantages of Incisional Biopsy

• Useful in diagnosing large lesions.
• Preserves aesthetics.
• Can be performed under local anesthesia.
• Lower risk of functional impairment than excisional biopsy.

Disadvantages of Incisional Biopsy

• Not therapeutic.

• Potential for sampling error, leading to false negatives.

• May miss areas of heterogeneity within the tumor, leading to misdiagnosis due to the limited sample size.

• May alter tumor anatomy or create a surgical challenge, distorting tissue planes and complicating future excisions.

• In cases of epithelial dysplasia, the severity of the epithelial changes or the presence of carcinoma has a positive correlation with the clinical appearance.

• A thin white plaque is less likely to harbor high-grade dysplasia than a thick white plaque or erythematous, ulcerated, and indurated regions.

• Selecting only the center of an ulcer results in an inadequate specimen due to necrotic tissues and inflammatory debris.

• The edge of an ulcer would be of more value in establishing a diagnosis, as it is a transition zone between normal and diseased tissues.

• Biopsy should focus on the area of greatest staining for dark staining lesions.

Excisional Biopsy

• This is the complete removal of a lesion for functional and aesthetic purposes, used to affirm the clinical diagnosis.

Indications for Excisional Biopsy

• Only when the lesion is confirmed benign.
• Used for smaller lesions (<1 cm in diameter).
• When accessibility and a consideration of the regional anatomy has been completed.
• Small, pedunculated, exophytic lesions in accessible areas.
• For any lesion that can be removed completely without harming the patient.
• Pigmented and small vascular lesions should be removed entirely.

Advantages of Excisional Biopsy

• Complete tissue removal.
• Provides a definitive diagnosis.
• Can be both diagnostic and curative, offering therapeutic benefits.

Disadvantages of Excisional Biopsy

• Invasive procedure.

• Anesthesia is required, either local or general, dependent on the lesion size and location.

• Longer recovery time with wound healing, sutures, and potential scarring.

• Risk of complications.

• Risk of poor cosmetic outcomes in visible areas like the face or hands.

• It is important to place biopsy samples in an appropriate fixative.

• Samples should be placed in 10% neutral buffered formalin immediately.

Goals of Fixation

• Prevent autolysis.
• Maintain the natural state of the tissue specimen.
• Facilitate proper staining.

Punch Biopsy

• This biopsy method uses a sharp circular blade to remove a small, deep, cylindrical tissue sample using a rotation motion.
• It can be used for either incisional or excisional purposes on a small lesion at an accessible site.
• A circular wound can make approximating easier.
• Punch biopsy is not appropriate for vesiculobullous diseases due to twisting action that can lead to distortion. Punch biopsy can rupture blisters

Contraindications for Punch Biopsy

• Freely Movable Tissue: Areas such as the tongue, buccal mucosa, or soft palate should not be used due to the difficulty in stabilizing.
• Highly Vascular Areas: Tongues, lips, and gingiva increase the risk of excessive bleeding or hematoma formation.
• Densely Innervated Areas: Areas, such as the mouth, increase the risk of nerve damage.
• Vesiculobullous Lesions: Lesions should not be used here because the risk of rupturing blisters can result in false negatives.

Indications for Punch Biopsy

• Diagnoses of Skin Disorders: Diagnosing inflammatory skin diseases like lichen planus and lupus erythematosus.
• Evaluation of Suspected Skin Cancer: Evaluation of Melanoma and basal cell carcinoma or squamous cell carcinoma.
• Assessment of Infectious Skin Conditions: Assessing diseases include Fungal infections and syphilis.

Advantages of Punch Biopsy

• Minimally Invasive
• Provides Full-Thickness Skin Sample
• Easy to Perform and Requires Minimal Equipment
• Faster Healing Than Excisional Biopsy
• Useful for Both Inflammatory and Malignant Conditions

Disadvantages of Punch Biopsy

• Limited Sample Size
• Potential for Misdiagnosis in Malignant Lesions
• May Require Sutures for Larger Punch Sizes
• Scarring

Aspiration Biopsy

• A diagnostic procedure which uses a needle and suction to extract cells, fluid, or tissue from a lesion or mass.
• Aspiration biopsies are used to diagnose infections, cysts, benign tumors, and malignancies.

Indications for Aspiration Biopsy

• Evaluating suspicious masses to differentiate them
• Diagnosing cystic vs. solid lesions; commonly in the thyroid and salivary glands
• Investigation of lymphadenopathy
• Fluid collection analysis

Advantages for Aspiration Biopsy

• Minimally invasive compared to surgical biopsy.
• Quick and simple, and is performed in outpatient settings.
• Low risk of complications, minimal bleeding and scarring.
• Useful for initial diagnosis, and guiding further investigations.

Fine Needle Aspiration Biopsy (FNAB)

• Uses a thin needle to extract cells or fluid for cytological analysis.

Fine Needle Cutting Biopsy (FNCB)

• A variation of FNAB, and uses an even more thin tip. Results can lead to limited histology analysis.

Indications for FNAB

• Commonly Salivary gland tumors, to know the tumor is a benign or malignant.
• Detection of thyroid gland nodules when diagnosing Thyroid malignancy.
• Differentiating between Benign from Malignant lesions in Lymph nodes.
• Prior to Surgical Exploration.

Analyzing Fluids obtained by FNAB

• Clear or straw colored: Benin cyst, serous fluid from thyroid or salivary cysts.
• Bloody (hemorrhagic): Vascular tumor, malignancy, or hemorrhagic cyst.
• Cloudy or turbid: Infective, inflammatory cysts (abscesses), or necrotic tumor.
• Milky: Lymphatic fluid leakage, seen in lymphangiomas (benign neoplasm).
• Gelatinous or viscous: Often seen in thyroid nodules.

Advantages of Aspiration Biopsy

• Patient comfort.
• Low risk of infection.
• Avoiding unnecessary damage to vital structures.

Disadvantages of Aspiration Biopsy

• Insufficient room in the oral cavity to properly perform the movements necessary to aspirate material.
• False-negative rates.

Fine Needle Cutting Biopsy (FNCB):

• A variation of FNAB, a cutting tip is used to obtain tissue fragments.
• 12or 16- gauge needles that use a trocar can be used to obtain cores of tissue.
• It can be examined by routine Histological methods.

Indications of FNCB

• Differentiation between Reactive inflammatory changes and recurrent malignancy,
• Larger tissue samples are needed for the analysis in Salivary gland tumors.
• Can aid in inconclusive Thyroid nodules.
• Useful for Bone marrow disorders, to diagnose leukemia or anemia.
• Simple outpatient procedure that can lead to rapid healing.
• It is also well tolerated by patients. Its is easier than FNC as interpretation is easier for most pathologist.

Disadvantages of FNCB:

• False Negative Reporting
• Possible tumor dissemination.

Differentations from the Type of Aspiration Biopsy

• FNAB uses a needle to aspirate material from the lesion. Whereas FNCB has a cutting mechanism.
• FNAB uses needles with 22–27 gauge. Whereas FNCB useds 12 –16 gauge.
• FNAB uses Loose cells and fluids whereas FNCB samples extracted tissue.
• FNAB can lead to less accurate readings vs the use of FNCB, a more accurate test designed for a definitive diagnosis.
• FNAB is more effective for liquid-filled lesions.

Drill Biopsy

• A technique that uses a rotating drill-like needle to extract a cylindrical core of tissue from hard or dense tissues like bone or deep tumors.
• This technique allows for better penetration into calcified or fibrotic tissues.

Indications for Drill Biopsy

• Bone tumors such as osteosarcoma and chondrosarcoma.
• Metastatic bone lesions from diseases such as breast or prostate cancer.
• Is effective when the standard aspiration is not sufficient
• It can be used for deep seated or fibrotic soft tissue masses

Advantages of Drill Biopsy

• Effective for Hard tissues.
• Minimally invasive compared to open surgical biopsy.
• Preserves tissue architecture for histological analysis.
• More accurate diagnosis of bone and dense tumors.

Disadvantages of Drill Biopsy

• Risk of bone fracture in fragile bones.
• Requires specialized equipment and expertise.
• Risk of complications like:
• Bleeding
• Hematoma formation
• Infection (osteomyelitis: bone infection)
• Pain and Discomfort