What is the Difference Between Bruise and Purpura?

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The main difference between a bruise and purpura lies in their causes and appearance. Here are the key differences:

Bruise:

  • A bruise, also known as a contusion, forms when small blood vessels under the skin tear or rupture, usually from a bump or fall.
  • Blood leaks into tissues under the skin, causing the black-and-blue color.
  • Bruises typically resolve within 2 to 4 weeks.
  • They are always the result of blunt force trauma.

Purpura:

  • Purpura consists of red or purple lesions that are similar to bruises, in that they are blood added to the skin tissues.
  • Purpura is not caused by an injury like most regular bruises.
  • It can be due to inflammation of the blood vessels, platelet disorders, clotting disorders, infections, and immune system reactions.
  • Purpura can appear as one larger patch (similar to a bruise) or several smaller dots (petechiae).

In summary, bruises are caused by external injuries and result from blood leaking into the surrounding tissues, while purpura is caused by internal factors and can appear as larger patches or smaller dots.

Comparative Table: Bruise vs Purpura

Here is a table comparing the differences between a bruise and purpura:

Feature Bruise Purpura
Definition A discolored patch of skin or tissue due to an injury Purple-colored lesions on the skin or mucous membranes
Causes Injury causing blood vessels to break and blood to leak out under the skin Bleeding from blood vessels due to inflammation, clotting disorders, infections, or immune disorders
Risk Factors Bleeding disorders, old age, and certain medications Autoimmune conditions, infections, certain medications, and irregular destruction of blood platelets
Diagnosis Physical exam and history of injury A biopsy and blood tests
Treatment Painkilling medication and ice if there is swelling in the injured area Corticosteroids, intravenous immunoglobulin, antibiotics, and pain relievers may be used depending on the cause
Prevalence Common and usually harmless Rarer and may indicate a more serious underlying condition