Can an Oral Leukoplakia Biopsy Miss Cancer or Dysplasia?

Yes. It is possible for an incisional biopsy (which removes only a small piece of tissue) to miss cancer or severe dysplasia in oral leukoplakia. Dysplasia refers to abnormal, precancerous cell changes; a biopsy might accurately show mild dysplasia or no dysplasia in the exact spot sampled, while missing a more severe area nearby ^[1].

If your biopsy results indicate no dysplasia or mild dysplasia, this can be reassuring if the lesion is small, uniform, and looks low-risk to your doctor. However, if the lesion is large, uneven, or highly suspicious, a single small biopsy might not tell the whole story ^[2]. In one study looking specifically at cases where the initial biopsy diagnosis did not match the final diagnosis after the whole lesion was removed, sampling error—meaning the biopsy was taken from a less severe part of the patch—accounted for 60% of those mismatches ^[3].

Why a Biopsy Might Underestimate Dysplasia

Oral leukoplakia lesions are often heterogeneous, meaning their cellular makeup is not the same across the entire patch. A single lesion can have areas of normal tissue, mild dysplasia, and severe dysplasia right next to one another.

Several factors contribute to a biopsy missing a more severe area:

• Sampling Location: In large, uneven, or mixed red-and-white lesions, the most abnormal cells might be concentrated in one small spot. If that specific spot is not sampled, the results will underestimate the true severity of the disease ^[3].
• Biopsy Depth: To accurately grade dysplasia or check for invasive cancer, a pathologist needs to see the full thickness of the oral mucosa (the mouth’s surface lining) and the underlying connective tissue. If a biopsy is too superficial or fragmented, it may fail to include enough tissue for an accurate diagnosis ^[4].
• Multifocal Disease: Some patients have multiple patches of leukoplakia scattered throughout the mouth. Testing one patch does not tell you what is happening in the others, and cancer can be present in unbiopsied areas ^[5].

The Challenge of Proliferative Verrucous Leukoplakia (PVL)

Proliferative verrucous leukoplakia (PVL) is a specific, aggressive form of leukoplakia that is especially prone to sampling errors. PVL typically starts as flat white patches that slowly spread over time, eventually becoming thick, warty (verrucous), and involving multiple areas of the mouth ^[6].

A major challenge with PVL is that early biopsies often show only hyperkeratosis (thickening of the surface lining) without any signs of dysplasia ^[7]. While this looks benign under a microscope, it is not harmless if the lesion continues to spread. PVL carries a substantial risk of eventually transforming into oral cancer and is diagnosed by observing its progressive clinical pattern over time, not just from a single biopsy ^[8]. Because early biopsies can look benign, a single “normal” result does not mean you are in the clear if the patches continue to grow ^[6][7].

How Doctors Target the Most Concerning Areas

To reduce the risk of sampling error, specialists carefully examine the lesion to target the most suspicious areas.

• Visual and Physical Clues: Doctors look for high-risk features within the leukoplakia, such as red patches (erythroplakia), ulcerations, nodules (lumps), firmness (induration), or areas that bleed easily ^[9].
• Taking Multiple Samples: For large, heterogeneous, or multifocal lesions, taking multiple biopsies from different sites provides a much more accurate picture of the disease ^[3].
• Advanced Imaging: In some specialist centers, doctors use narrow-band imaging (NBI) as an adjunct tool. NBI uses special light to highlight abnormal blood vessel patterns, which can help guide the doctor to the best spot to biopsy. However, NBI does not replace a physical tissue biopsy ^[10].

When is Reassessment or Removal Warranted?

Because of the risk of sampling error, a biopsy report of “benign” or “mild dysplasia” is not the end of your evaluation if your doctor remains concerned ^[2]. You should seek prompt specialist reassessment if:

• The clinical picture doesn’t match the pathology: If your doctor strongly suspects a high-grade problem based on how the lesion looks and feels, but the biopsy comes back as mild or benign (clinicopathologic discordance), this should always prompt a second look or repeat biopsy ^[2][11].
• The lesion changes: Contact your treating clinician promptly if the leukoplakia rapidly grows, becomes red, develops a rough texture, or if you develop a non-healing ulcer, persistent bleeding, increasing pain, or a lump ^[12].
• The lesion persists: If a suspicious patch remains despite clinician-directed management of local trauma (like sharp teeth), it requires prompt evaluation ^[2]. (Note: Tobacco and alcohol are major risk factors that should be stopped, but eliminating them should not delay the biopsy of a suspicious lesion).

For some persistent or high-risk leukoplakias, the clinician may recommend complete surgical removal (excision). Excision reduces the chance of missing severe disease within that specific patch of tissue ^[5][13]. However, excision is just one individualized option. It is not always possible for large or multifocal lesions, and it does not guarantee that new lesions won’t form elsewhere. Whether a lesion is monitored, biopsied again, or completely removed, long-term surveillance is almost always needed ^[5].