Finding an unexpected black spot on the soft, pink lining of your inner cheek can be a disconcerting discovery. The oral mucosa, or the lining of the mouth, is a highly vascular and sensitive tissue, and any discoloration is noticeable because it contrasts sharply with the surrounding pink environment. Most localized pigmentations in the mouth are entirely harmless. However, because a dark spot can occasionally signal a serious underlying issue, any newly discovered or changing lesion warrants professional medical attention for a definitive diagnosis.
Benign Causes of Pigmentation
Many dark spots in the mouth are simply accumulations of melanin, the natural pigment that gives color to skin and hair. The most common form is the melanotic macule, often referred to as an oral freckle. These typically appear as flat, well-defined brown or black spots, usually measuring less than a quarter of an inch in diameter. They result from increased melanin production without an increase in pigment-producing cells.
Another category of harmless spots includes Pigmented Nevi, which are the intraoral equivalent of a common skin mole. These lesions are usually slightly raised and can range in color from brown to bluish-gray or nearly black. Although nevi are benign, a healthcare provider may still recommend a biopsy to confirm their nature and rule out other possibilities.
Post-inflammatory hyperpigmentation occurs when the body increases melanin production following localized irritation, infection, or trauma. This darkening is essentially the tissue’s reaction to a prior injury and is more frequently observed in individuals with naturally darker complexions. Additionally, certain medications, such as some anti-malarial drugs, can cause a more widespread, diffuse darkening of the oral tissues. These benign pigmentations generally remain stable over time and do not produce symptoms like pain or bleeding.
Spots Caused by Trauma or Foreign Material
Some black spots result from a physical event, either a direct injury or the embedding of a foreign substance in the tissue. A common example is an Amalgam Tattoo, which occurs when minute particles of silver dental filling material become lodged in the mucosal lining. The resulting spot is typically a flat, painless, bluish-black or gray discoloration. These tattoos are most often found near a tooth that has, or previously had, an amalgam restoration, and the metallic fragments can sometimes be confirmed with a dental X-ray.
Another cause is a hematoma, commonly known as a blood blister. This dark, raised lesion forms when minor trauma, such as accidentally biting the cheek, causes blood vessels to rupture just beneath the mucosal surface. The resultant spot is dark red or purplish-black due to the trapped blood and will typically resolve on its own as the body reabsorbs the blood. Unlike other pigmented lesions, a hematoma has a clear, recent history of injury and should fade significantly within one to two weeks.
When a Black Spot Requires Immediate Attention
While most black spots are benign, lesions exhibiting change require urgent professional evaluation to exclude oral mucosal melanoma. Oral melanoma is a rare but highly aggressive form of cancer that originates from the pigment-producing cells in the mouth. Early detection is paramount because these lesions are frequently diagnosed at an advanced, invasive stage.
Suspicious lesions often display characteristics that can be remembered using a modified version of the ABCDE criteria used for skin cancer. The presence of Asymmetry, where one half of the spot does not match the other, is a warning sign. Border irregularity, meaning the edges are ragged, notched, or poorly defined, is also a concerning feature.
Another sign is Color variation, such as shades of brown, black, blue, or red appearing within the same lesion, rather than a uniform color. Diameter greater than 6 millimeters is a general threshold.
The most important indicator is Evolution, or any noticeable change over a short period. This includes rapid growth in size, alteration in color or shape, or the onset of symptoms like bleeding, pain, or the development of a raised nodule. Any black spot exhibiting these changing features must be seen by a specialist without delay.
What to Expect During a Medical Evaluation
A medical evaluation for a pigmented spot typically begins with a thorough history, including questions about how long the spot has been present, if it has changed, and any associated symptoms. The healthcare provider, often a dentist or an oral pathologist, will conduct a detailed visual examination, noting the lesion’s exact size, color, and location. They may use a specialized tool, such as a handheld dermatoscope, to examine the lesion’s structure more closely.
The provider may take a photograph of the spot and measure it precisely to monitor for future changes. If the lesion is suspicious, or if a definitive diagnosis cannot be made clinically, the next step is usually a biopsy. A biopsy involves removing a small portion or the entire lesion for microscopic analysis. This is the only way to confirm the exact nature of the cells and definitively rule out malignancy. If the lesion is determined to be benign, the treatment may simply be monitoring.