Melasma is not cancerous, not a sign of cancer, and does not turn into cancer. It is a completely benign skin condition caused by overactive pigment-producing cells, resulting in flat, darkened patches on the face. That said, certain skin cancers can visually mimic melasma, which is why getting a proper diagnosis matters.
What Melasma Actually Is
Melasma happens when melanocytes, the cells responsible for skin color, go into overdrive and produce excess pigment. This pigment deposits unevenly, creating blotchy brown or grayish-brown patches that most commonly appear on the cheeks, forehead, nose bridge, and upper lip. The patches are always flat, never raised, and they don’t cause pain, itching, or any physical discomfort.
Under a microscope, melasma looks nothing like cancer. The number of melanocytes in the affected skin typically isn’t even increased. Instead, the existing melanocytes are simply larger, more branched, and more active than normal. There’s little to no inflammation present. This is fundamentally different from melanoma, where abnormal cells multiply uncontrollably and invade surrounding tissue.
Why People Confuse Melasma With Something Dangerous
Melasma can look alarming because it appears as dark, irregularly shaped patches that seem to spread over time, especially with sun exposure. That pattern understandably raises worry. But melasma behaves very differently from melanoma or other skin cancers. Melasma patches are typically symmetrical, appearing in roughly the same pattern on both sides of the face. They have a relatively uniform color within each patch, usually a consistent shade of brown. And they stay flat.
Melanoma, by contrast, follows a distinct pattern dermatologists call the ABCDEs:
- Asymmetry: one half of the spot looks unlike the other half
- Border: the edges are irregular, scalloped, or poorly defined
- Color: the spot contains varying colors, such as shades of tan, brown, black, white, red, or blue within the same lesion
- Diameter: the spot is usually larger than 6 millimeters (about the size of a pencil eraser) at diagnosis, though it can be smaller
- Evolving: the spot is actively changing in size, shape, or color, or looks noticeably different from other spots on the skin
Melasma patches don’t typically exhibit these characteristics. They tend to be symmetrical, uniform in color, and stable in their overall appearance (though they may darken or lighten with sun exposure or hormonal changes).
How Dermatologists Confirm It’s Melasma
Melasma is almost always diagnosed by visual examination alone. A dermatologist can usually identify it based on the pattern, location, and appearance of the patches without any lab work or biopsy. In some cases, a Wood lamp (a handheld ultraviolet light) is used to determine whether the excess pigment sits in the upper layers of the skin, deeper layers, or both. This helps guide treatment decisions but isn’t needed to confirm the diagnosis.
A skin biopsy is only performed if the diagnosis is uncertain, specifically to rule out other conditions that might look similar. Some dermatologists also check thyroid function, since mild thyroid abnormalities have been linked to melasma, particularly in cases associated with pregnancy or hormonal contraceptives.
What Causes Melasma
Hormones and sunlight are the two primary drivers. An increase in estrogen and progesterone, which happens during pregnancy, while taking hormonal birth control, or during hormone replacement therapy, is thought to trigger the overproduction of pigment. This is why melasma is sometimes called the “mask of pregnancy.” Stress can also play a role by raising cortisol levels, which may stimulate melanocytes.
UV exposure from sunlight or tanning beds accelerates the process and worsens existing patches. Even people whose melasma has faded will often see it return with sun exposure, which is why sun protection is the single most important factor in managing the condition long-term.
Who Gets Melasma
Melasma overwhelmingly affects women. The female-to-male ratio is commonly cited as 9 to 1, though a large multicenter study of 953 patients in Brazil found the ratio closer to 39 to 1. People with medium to darker skin tones are most susceptible, particularly those with Fitzpatrick skin types III and IV (olive to light brown complexions). These skin types account for over 75% of melasma cases in clinical studies. People from regions with intense year-round sun exposure are especially prone.
When a Dark Patch Needs a Closer Look
While melasma itself is harmless, some skin cancers can mimic its appearance. You should have a dermatologist evaluate any dark patch on your skin that is raised or has texture to it, contains multiple distinct colors within the same spot, has uneven or jagged borders, is changing rapidly in size or shape, or bleeds, itches, or feels different from the surrounding skin. Melasma is always flat, painless, and non-itchy. Any deviation from that warrants a professional evaluation to rule out something more serious.
If you do have melasma, earlier treatment tends to produce better results. The longer the pigment has been accumulating, the more difficult it becomes to reduce.