A bruise, medically known as a contusion, forms when small blood vessels, called capillaries, beneath the skin break due to an injury. This rupture allows blood to leak into the surrounding tissues, becoming trapped and visible as a discolored mark. Most people recognize bruises as temporary marks that naturally fade over time. This article explores whether a mark resembling a bruise can truly persist indefinitely and what underlying factors might contribute to such lingering discoloration.
The Science of Bruise Healing
When capillaries beneath the skin rupture, blood leaks into surrounding tissues. This trapped blood initially appears red or purplish because the hemoglobin, an iron-rich protein in red blood cells, is still oxygenated. As the blood loses oxygen and the body begins to break down hemoglobin, the bruise typically changes color.
The breakdown of hemoglobin leads to a spectrum of colors. Hemoglobin is converted into biliverdin, which gives the bruise a green hue, usually appearing around 5 to 10 days after the injury. Biliverdin then transforms into bilirubin, resulting in a yellowish appearance. Finally, these pigments are further processed into hemosiderin, which can appear golden-brown. As these breakdown products are gradually reabsorbed by the body’s immune cells, the bruise fades and typically disappears completely within a few weeks, though larger bruises may take longer to resolve.
Conditions That Can Mimic Permanent Bruises
While a true bruise is temporary as the body reabsorbs the blood, certain conditions or injury outcomes can leave long-lasting marks that resemble bruises. These persistent discolorations are not traditional bruises but residual effects or symptoms of other issues.
One common cause of persistent bruise-like discoloration is hemosiderin staining. Hemosiderin is an iron-storage complex that forms when hemoglobin from broken red blood cells is broken down and deposited in the skin’s deeper layers. This iron-containing pigment can appear brownish or rust-colored and is often seen after significant or repeated bruising, or in areas with compromised circulation, such as the lower legs. In some cases, the body may not fully clear this pigment, leading to discoloration that can last for months or even years.
Another condition that can mimic a lingering bruise is post-inflammatory hyperpigmentation (PIH). This occurs when trauma or inflammation to the skin, such as that caused by a bruise, triggers an overproduction of melanin, the pigment responsible for skin color. The result is a dark spot or patch that can range from light brown to black, depending on skin tone and the severity of the inflammation. PIH is more common and can be more pronounced in individuals with darker skin tones, and while it often fades over time, this process can take several months to years.
In instances of severe trauma, the injury causing a bruise might also damage skin tissue, leading to scar formation. While not a bruise, a scar can be discolored and permanent. Additionally, what appears to be a persistent bruise could be a symptom of an underlying medical condition. Certain vascular malformations, chronic venous insufficiency (where blood pools in the legs due to malfunctioning vein valves), or some skin conditions can manifest as persistent discoloration mistaken for a bruise. These are not actual bruises but indications of systemic issues.
When to Consult a Doctor
While most bruises are harmless and resolve on their own, there are situations when a persistent or unusual mark warrants medical attention. It is advisable to consult a healthcare professional if a bruise does not begin to fade or appears to worsen after two to four weeks.
Seek medical advice for a “bruise” if it:
- Is accompanied by severe pain, significant swelling, or numbness, or affects the function of a joint or limb.
- Is unexplained or frequent, especially occurring without apparent injury or with only very minor trauma.
- Is accompanied by other symptoms like fever, bleeding from other areas, extreme fatigue, or unexplained weight loss.
- Changes in size, shape, or color, or becomes raised.