The swelling is likely to be post trauma haematoma
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The knot or lump following fighting is likely to be due to traumatic haematoma (localised collection of clotted blood). It's usually associated with reddish discolouration of the overlying skin. I hope there is no disfigurement of jaw line , presence of which could imply underlying fracture
The clot usually undergoes liquefaction followed by absorption which will lead to resolution of the swelling. Local hot water fomentation and analgesic
will be very helpful.
Do get back to me if you need any further assistance, will be glad to assist you.
Dr T Shobha Deepak