Macula

A macule (from Latin macula – spot) is a primary cell-free morphological element of a skin rash characterized by a change in skin color in a limited area.

The main distinguishing feature of the spot is that it does not rise above the level of healthy skin and is not sunken (not palpable). If you close your eyes and run your finger over the spot, you will not feel any change in the relief of the skin.

Etiology and pathophysiology

Color change can be caused by a variety of mechanisms:

• Vascular spots: Associated with temporary or persistent dilation of blood vessels (roseola, erythema, telangiectasia). They disappear or become pale when pressure is applied (diascopy).
• Hemorrhagic spots: Occur when red blood cells escape from vessels into tissues (petechiae, ecchymoses). Do not disappear when pressure is applied.
• Age spots: Associated with changes in the amount of melanin pigment. May be hyperpigmented (freckles, chloasma) or depigmented (vitiligo).

Clinical significance

The size of the spot has implications for terminology: spots up to 1-2 cm in diameter are usually called roseola (if vascular) or simply macules, larger foci are called erythema. Macules are the most common element of the rash and occur in a huge range of diseases: from infections (measles, rubella) to allergic reactions.