#Clinical Features—­Local Phenomena.#—­The most generally accepted classification of burns is that of Dupuytren, which is based upon the depth of the lesion.  Six degrees are thus, recognised:  (1) hyperaemia or erythema; (2) vesication; (3) partial destruction of the true skin; (4) total destruction of the true skin; (5) charring of muscles; (6) charring of bones.

It must be observed, however, that burns met with at the bedside always illustrate more than one of these degrees, the deeper forms always being associated with those less deep, and the clinical picture is made up of the combined characters of all.  A burn is classified in terms of its most severe portion.  It is also to be remarked that the extent and severity of a burn usually prove to be greater than at first sight appears.

Burns of the first degree are associated with erythema of the skin, due to hyperaemia of its blood vessels, and result from scorching by flame, from contact with solids or fluids below 212 F., or from exposure to the sun’s rays.  They are characterised clinically by acute pain, redness, transitory swelling from oedema, and subsequent desquamation of the surface layers of the epidermis.  A special form of pigmentation of the skin is seen on the front of the legs of women from exposure to the heat of the fire.

Burns of Second Degree—­Vesication of the Skin.—­These are characterised by the occurrence of vesicles or blisters which are scattered over the hyperaemic area, and contain a clear yellowish or brownish fluid.  On removing the raised epidermis, the congested and highly sensitive papillae of the skin are exposed.  Unna has found that pyogenic bacteria are invariably present in these blisters.  Burns of the second degree leave no scar but frequently a persistent discoloration.  In rare instances the burned area becomes the seat of a peculiar overgrowth of fibrous tissue of the nature of keloid (p 401).

Burns of Third Degree—­Partial Destruction of the Skin.—­The epidermis and papillae are destroyed in patches, leaving hard, dry, and insensitive sloughs of a yellow or black colour.  The pain in these burns is intense, but passes off during the first or second day, to return again, however, when, about the end of a week, the sloughs separate and expose the nerve filaments of the underlying skin.  Granulations spring up to fill the gap, and are rapidly covered by epithelium, derived partly from the margins and partly from the remains of skin glands which have not been completely destroyed.  These latter appear on the surface of the granulations as small bluish islets which gradually increase in size, become of a greyish-white colour, and ultimately blend with one another and with the edges.  The resulting cicatrix may be slightly depressed, but otherwise exhibits little tendency to contract and cause deformity.