PRIMARY OR ELEMENTARY LESIONS [Primary or Elementary Lesions]
MACULES (Spots; Erythematous spots; Stains; Maculae)
Definition. Macules are variously sized, shaped and tinted alterations in the color of the skin with little or no elevation.
They vary greatly in size from that of a pin-point to patches several square inches in dimension. There is an equal variation in shape, for although they are generally rounded they may be irregular, avoid or linear. They vary in color from a light pink or red to a dark brown or black. These colors may or may not temporarily disappear on pressure. The duration of macules may be long or short, running an acute, subacute or chronic course. They may or may not be attended with subjective symptoms; usually the latter are wanting. Macules may be due to hyperemia, to extravasations of blood, to dilatation of blood-vessels or to changes in the pigmentation of the skin. According to these factors they are variously designated. Erythema or roseola are terms used to denote acute hyperemia of the skin. Their color is red, if due to arterial congestion; bluish red, if due to venous distention; and they always disappear on pressure. If a fluid exudation from the blood-vessels is present in the skin, there is some swelling and occasionally a slight elevation of the surface. Sometimes the coloring matter of the blood escapes with the exudation and gives a yellowish shade to the patches. Erythema occurs either in irregular circumscribed patches or is more or less generally diffused over the surface. Sometimes it forms a ring or halo about an inflamed area of skin. Roseola occurs during the course of the eruptive fevers in round or avoid spots, rarely exceeding a finger-nail in size.
Purpura signifies an extravasation of blood into the superficial tissues of the skin, giving rise to variously sized muscles. Of a reddish-purple color at first, they change to various shades of so-called “black and blue,” as absorption of the blood-coloring matter occurs. In partial venous obstruction only the coloring matter of the blood may escape and show in yellowish-colored macules. When the haemorrhage spots are small and round, they are called petechiae; when larger in size, ecchymoses; and when linear in shape, vibices. Purpuric spots may be primary in occurrence or secondary to inflammatory lesions. Vascular nevi is the name given to congenital dilatation of the small blood-vessels of the skin, and telangiectases to a similar acquired condition of the blood-vessels. Macules produced by a change in the normal coloring of the skin may be due to increase or loss of pigment. Chloasma is an example of excess of pigment, and vitiligo of diminution of pigment. The changes in color may be permanent or of short duration; congenital as in moles or acquired as in freckles. Diffuse staining of the skin, as in jaundice, malarial melanosis, etc., are macular in nature but are called discolorations of the skin. Pigmentary macules are sometimes secondary to other cutaneous diseases, as the stains seen after acne, lichen planus and urticaria. Contact of the skin with chemicals, irritants or dyes may be followed by increase of pigment. Loss of pigment may attend or follow atrophic changes as seen in cicatrices and scleroderma.
Occasionally macules tend to merge or develop into papules (maculopapules or erythematopapules) and when this characteristic predominates, the eruption is described as erythemopapular or maculopapular.