(Abrasions; Erosions; Scratch-marks)
Definition. Excoriations are superficial, irregular or linear solutions of continuity, due to traumatic or mechanical factors and vary in size, shape and depth according to the nature and degree of the causal element.
Excoriations occur chiefly in diseases attended with itching of the skin, and commonly result from scratching with the nails; but may be caused by rubbing one surface against another or against a foreign substance. Thus pricks or scratches from pins, needles and other ordinary articles may cause isolated lesions; an abraded surface may arise from slight trauma known as “barking the shin”; or constant rubbing like the friction of clothing, especially if papules or vesicles already exist, may give rise to excoriations. Such lesions are of diagnostic value in many instances, and when due to the finger-nails, are only found on parts accessible to the fingers as illustrated in pediculosis and scabies. Excoriations are significant of itching and this fact alone may help in the diagnosis of diseases that have other symptoms in common. It is well to recall that excoriations may exist without previous skin lesions as in pruritus, although they are usually secondary to some lesion or lesions.
Excoriations vary in their shape and size as much as in their location; thus they are usually pointed in papular diseases like eczema; linear in pediculosis; surrounded by a red areola in ecthyma; and if hemorrhage ensues, they will show dark brown crusts as in dermatitis gangrenosa. Long continued scratching or rubbing of a given area as in pediculosis, pruritus or eczema will cause inflammatory infiltration, thickening and a variable degree of pigmentation. In aggravated cases of pediculosis this pigmentation may be so extensive as to resemble. Addison’s disease. Excoriations are often accompanied by pustules because the breaks in the skin afford opportunity for infection by pus cocci. Ordinarily no scars, may be expected to follow superficial excoriation but if the latter involves the corium, slight white atrophic spots may result.