by Jason Wasserman MD PhD FRCPC
February 25, 2026
An oral melanotic macule is a benign (noncancerous), flat, pigmented spot found on the lining of the mouth.
The inside of the mouth is covered by a thin protective layer called the epithelium. In an oral melanotic macule, there is a small, localized increase in melanin, which is the pigment that gives color to skin and mucous membranes. This extra pigment causes a visible brown, gray, or blue patch.
An oral melanotic macule is not cancer and is not considered a precancerous condition. It does not develop into melanoma or any other type of cancer.
Where does an oral melanotic macule occur?
Oral melanotic macules can occur anywhere in the oral cavity, but they are most commonly found on the lips, especially the lower lip. They may also appear on the gums, hard palate, or inner cheeks.
What does an oral melanotic macule look like?
An oral melanotic macule appears as a well-defined, flat patch of discoloration. The color may range from light brown to dark brown, or from gray to blue.
These spots are usually small, often less than 1 centimeter in size. They are smooth and do not form a raised lump. The size and color typically remain stable over time.
What causes an oral melanotic macule?
The exact cause of oral melanotic macules is not fully understood. They result from increased melanin in a small area of the oral lining.
In lesions located on the lips, chronic sun exposure may contribute to pigment production. In other areas of the mouth, the increased pigment may occur without a clear trigger. Oral melanotic macules are not caused by infection and are not related to systemic diseases in most cases.
Does an oral melanotic macule need to be removed?
Oral melanotic macules are harmless and usually do not require treatment.
However, if the diagnosis is uncertain or the lesion has unusual features such as rapid growth, irregular borders, or color changes, a biopsy may be recommended. A biopsy allows a pathologist to examine the tissue under a microscope and confirm that the lesion is benign.
Removal may also be considered for cosmetic reasons, particularly for lip lesions.
How is this diagnosis made?
The diagnosis may be suspected based on the clinical appearance during a dental or medical examination. However, because other pigmented lesions of the oral cavity can appear similar, a biopsy is sometimes performed to confirm the diagnosis.
The final diagnosis is made after microscopic examination by a pathologist.
Microscopic features
Under the microscope, an oral melanotic macule shows an increased amount of melanin pigment in the basal layer of the epithelium. The basal layer is the deepest layer of the surface lining.
The number of melanocytes, which produce melanin, is usually normal. This is an important feature because it helps distinguish an oral melanotic macule from other pigmented lesions, such as a melanocytic nevus or malignant melanoma, which have an increased number of melanocytes.
The overlying epithelium appears normal and does not show dysplasia or atypical cells. In the underlying connective tissue, called the lamina propria, small amounts of pigment may be seen within macrophages, immune cells that clear pigment.
Special stains, such as the Fontana-Masson stain, can be used to highlight melanin pigment if needed. Tests for iron are typically negative, which helps confirm that the pigment is melanin rather than a blood-related pigment.
Is an oral melanotic macule associated with cancer?
No. Oral melanotic macules are benign and are not associated with an increased risk of cancer. They do not have malignant potential, meaning they do not turn into melanoma or other cancers over time.
Questions you may want to ask your doctor
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Is the diagnosis certain, or do I need a biopsy?
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Are there any features that make this lesion concerning?
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Should the lesion be monitored for changes?
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Do I need follow-up examinations?
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