A bruise forms when small blood vessels under the skin break, leading to blood pooling and visible discoloration. Melanoma is a serious type of skin cancer that originates from pigment-producing cells. Understanding the differences between them is important, as melanoma can sometimes resemble a bruise. This article clarifies if melanoma can look like a bruise and highlights their key distinctions.
Characteristics of Bruises
Bruises, medically termed ecchymoses or contusions, result from trauma that damages small blood vessels beneath the skin. When these vessels rupture, blood leaks into surrounding tissues, becoming trapped and causing a visible mark. A bruise’s appearance evolves through a predictable color progression as the body breaks down and reabsorbs the pooled blood.
Initially, a bruise may appear reddish or purplish shortly after injury. Over the next few days, it shifts to shades of blue or black as hemoglobin changes. As healing continues, the bruise can turn greenish, then yellowish or light brown, before fading within approximately two weeks.
Bruises are often accompanied by pain or tenderness to the touch and may present with some swelling at the injury site.
Characteristics of Melanoma
Melanoma is a form of skin cancer that develops from melanocytes, the specialized cells responsible for producing melanin, the pigment that gives skin its color. This cancer can manifest as a new spot on the skin, or it may arise from changes in an existing mole. While many melanomas are dark, their appearance can vary considerably. Melanoma can also mimic other benign conditions, appearing as a dark, irregular spot that might be mistaken for a bruise, particularly under a nail or on the palms or soles. Dermatologists use the ABCDE rule to identify potential melanomas:
Asymmetry: One half of the spot does not match the other.
Border irregularity: Edges are uneven, notched, or poorly defined.
Color variation: Multiple shades of brown, black, tan, red, white, or blue within the same lesion.
Diameter: Larger than 6 millimeters, roughly the size of a pencil eraser.
Evolving: Any changes in size, shape, color, or other characteristics over time.
Distinguishing Melanoma from Bruises
Differentiating between a bruise and melanoma requires careful observation of several features. A bruise typically forms as a direct result of trauma, causing blood vessels to break and leak. In contrast, melanoma arises from uncontrolled growth of pigment cells and does not require an injury to develop. Pain and tenderness are common symptoms of a bruise, particularly when touched. Melanoma, however, is generally painless in its early stages, although it can later become itchy, tender, or bleed.
The way a spot changes over time provides an important clue. Bruises undergo a characteristic color transformation and will consistently fade and resolve within a few days to a couple of weeks as the body reabsorbs the blood. Melanoma, conversely, does not resolve on its own; it tends to grow, change in shape or color, or persist indefinitely.
While bruises can appear anywhere, melanoma can sometimes occur in less common locations that might lead to confusion. For instance, subungual melanoma, a type of melanoma that develops under the nail, can present as a dark line or streak, easily mistaken for a bruise or blood blister from a minor injury. Unlike a bruise under a nail, which will typically grow out with the nail or fade as the blood is absorbed, subungual melanoma will not resolve and may even cause the nail to deform or lift.
The texture and feel of the spot can also offer insights. Bruises typically feel flat or may present as a slightly raised swelling. Melanoma, while sometimes flat, can also be raised, firm, or have an irregular surface that may scale, crust, or ooze. Bruises are temporary and part of the body’s healing process after an injury, whereas melanoma is a persistent and potentially progressive lesion that requires medical intervention.
When to Consult a Doctor
Seek medical attention for any dark spot on the skin that appears suspicious or undergoes changes. A medical evaluation is recommended if a dark spot does not fade or resolve within two to three weeks, unlike a typical bruise. If a dark spot appears without any known injury or trauma, it warrants professional assessment.
Any lesion exhibiting the ABCDE signs of melanoma should be examined by a healthcare provider. If a spot becomes painful, itchy, bleeds, or oozes, these are additional reasons to consult a doctor. A dark spot under a fingernail or toenail not clearly attributable to an injury, or one that does not grow out with the nail, also requires medical evaluation.