A black or dark spot on the lip, medically referred to as hyperpigmentation, is a common finding that often prompts concern. The thinner nature of lip skin makes it particularly susceptible to discoloration from various internal and external factors. This discoloration can range widely in significance, from a harmless cosmetic change to a sign of a systemic issue or, in rare instances, a serious malignancy. Understanding the characteristics that differentiate these spots is important, but this information should never replace an in-person medical diagnosis from a qualified healthcare professional.
Common and Benign Causes
Many dark spots on the lips are localized and represent benign changes in pigment cells or blood vessels. A frequent cause is a labial melanotic macule, a flat, dark gray-brown lip freckle caused by increased melanin production. These macules are uniform, stable, and associated with sun exposure.
Another common finding is a venous lake, a small collection of dilated blood vessels that presents as a soft, dark blue or purple spot, often slightly raised. Venous lakes typically develop on the lower lip of older individuals due to chronic sun damage. They are a vascular issue, not a pigment issue.
Darkening can also occur following trauma or inflammation, known as post-inflammatory hyperpigmentation (PIH). This results from injuries like a cold sore, burn, persistent lip biting, or severe chapping. The discoloration represents residual melanin deposited in the deeper skin layers and usually fades slowly over many months.
Less common but benign are angiokeratomas, which are dark red to black, wart-like spots caused by dilated blood capillaries close to the surface. These growths are generally harmless and are distinct from pigment-based spots.
Systemic and Drug-Induced Pigmentation
Dark spots on the lip may signal an underlying systemic condition or represent a side effect of certain medications. Drug-induced hyperpigmentation is a documented side effect of several drug classes, including antimalarials, certain chemotherapy agents, and the antibiotic minocycline.
Minocycline, often used for long-term acne treatment, can cause a blue-grey or muddy brown discoloration in the oral mucosa and skin due to the deposition of drug metabolites. This discoloration can sometimes be permanent, even after the medication is discontinued, depending on the cumulative dosage over time.
Pigmentation can also manifest due to systemic syndromes or endocrine disorders. Peutz-Jeghers Syndrome (PJS), a rare inherited disorder, causes freckle-like spots around the mouth, lips, hands, and feet, accompanying an increased risk of gastrointestinal cancers.
Addison’s Disease, an adrenal gland disorder, causes a lack of cortisol, leading to increased production of melanocyte-stimulating hormones (MSH). This hormonal imbalance causes diffuse darkening of the skin and oral mucosa, including the lips. General hormone fluctuations, such as during pregnancy, can also lead to lip hyperpigmentation.
Recognizing Potential Malignancy
While most lip spots are benign, any new or changing dark spot warrants attention due to the rare risk of mucosal melanoma. Melanoma is a serious cancer originating from pigment-producing cells, and on the lips, it is often more aggressive than on other body sites. Recognizing a potentially cancerous lesion involves observing changes over time using modified “ABCDE” criteria.
ABCDE Criteria
Asymmetry is a concern if one half of the spot does not match the other, suggesting uncontrolled growth.
The border should be examined for irregularity, looking for notched, blurred, or ragged edges.
Color variation is a significant red flag, particularly if the spot contains multiple shades of black, brown, tan, white, red, or blue.
A diameter greater than 6 millimeters raises suspicion, although melanomas can present when smaller.
“Evolving” describes any change in size, shape, color, or height over weeks or months, or the sudden onset of new symptoms. Concerning features also include the spot bleeding easily, failing to heal, or developing an open sore.
When Professional Consultation is Necessary
Seeking professional medical evaluation is necessary for any black spot on the lip that causes uncertainty or exhibits concerning features. A visit to a dermatologist or general practitioner is warranted if you observe rapid growth or a sudden change in the spot’s texture.
Significant red flags requiring immediate attention include bleeding without trauma, the development of an ulceration, or a spot that does not heal within a reasonable timeframe. Even a long-present spot that suddenly begins to itch or become tender should be checked by a physician.
During the consultation, the doctor will thoroughly examine the lesion, often using a specialized handheld microscope called a dermatoscope. The dermatoscope assesses patterns of pigment distribution and blood vessels not visible to the naked eye, assisting in the initial distinction between benign and suspicious lesions.
If a spot remains suspicious following visual and dermoscopic examination, a biopsy will be performed. This involves removing a small tissue sample for laboratory analysis, which is the definitive procedure to confirm the exact nature of the spot and determine if further treatment is necessary.