Bruises are the result of extravasation of blood into the skin. Conventional usage often groups petechiae and bruises (or ecchymoses) together as purpura and defines them as follows:
- Petechiae: flat, red, or reddish purple; 1 to 3 mm; nonblanching
- Ecchymoses: larger than petechiae, local extravasation, nonpulsatile, sometimes palpable, color depends on age of lesion
- <1% nonmobile babies
- 17% cruising and crawling infants
- 53% walkers
- Majority of school age children
Underlying bleeding disorders (e.g., von Willebrand disease, platelet disfunction, thrombocytopenia), child abuse/trauma, medications, infections, etc. may all be risk factors leading to bruising in childhood.
- Hemophilia is an X-linked disorder affecting males.
- von Willebrand disease may be autosomal dominant.
- Other platelet disorders have a variety of inheritance patterns.
Extravasation of blood from blood vessels leading to a collection of blood below the surface of the skin
- Disorders of blood vessels and surrounding tissue
- Platelet abnormalities (function, number)
- Coagulation disorders
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