Similar to the causes of necrosis (cell death) in bone, a variety of conditions ranging from infection, unusual immune responses (such as sepsis, cardiovascular conditions, unwanted effects of medications through to exposure to high-energy radiation can cause necrosis of soft tissues.
Soft tissue necrosis can affect the skin, including the deep layers of skin, the mucosa (such as the lining of the mouth) and generally all soft tissues and organs in the body. Affected skin may initially show painful signs of inflammation, before the area turns gradually dark and fluid-filled blisters (bullae) develop, eventually the dead tissue turns black and the necrotic region is no longer painful because the peripheral nerves have also stopped working. Necrosis of the (oral) mucosa follows a similar pattern.
Medications used in radical chemotherapy, including antiangiogenic substances (substances that block the growth of blood vessels; a well-known example of such a drug is bevacizumab, used in the treatment of a range of malignancies), cause damage to the oral mucosa, ranging from inflammation and ulcers to severe mucositis and necrosis.
Radiotherapy applied to the head and neck region, in particular radical irradiation with high doses and especially combined with chemotherapy can cause osteoradionecrosis (ORN) of the jaws and other target bones. Skin in the irradiated area, the oral mucosa and other specialised soft tissues, in particular the salivary glands, in the head and neck region are all vulnerable to long-term damage by exposure high-energy radiation; this damage may include soft tissue necrosis with or without osteoradionecrosis of the jaws.
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