Contusions: mechanism, location and characteristic features
THE CONTEXT
Contusions are blood effusions caused by blunt trauma. The passage also describes skin changes that may resemble abrasions.
Abrasion mimics
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Ant erosions lack a vital reaction.
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In infants, slight inflammation and excoriation may occur in the napkin area at death. After death, these areas become dry, depressed and parchment-like, with colour ranging from pale yellow to deep copper.
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Pressure sores are included in the differential diagnosis of abrasions.
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Drying of scrotal skin can produce hardened, reddish-brown discolouration resembling an abrasion.
Mechanism and distribution of contusions
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A contusion is an effusion of blood into tissues caused by blunt-trauma rupture of vessels, including veins, venules and arterioles.
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Contusions are classified as intradermal, subcutaneous or deep.
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They can occur in skin, muscles and internal organs, including the lung, heart and brain.
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A bruise is usually situated in the corium and subcutaneous tissue above the deep fascia, often in the fat layer.
Clinical and gross features
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A contusion produces painful swelling with crushing or tearing of subcutaneous tissues, usually without destruction of the skin.
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Extravasated blood spreads diffusely through tissue spaces, giving blurred margins.
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Bruises may coexist with abrasions, forming an abraded contusion, or with lacerations.
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Injury to a large vessel may form a tumour-like blood collection called a haematoma. Petechial bruises have a finely mottled or stippled appearance.