Eczema. Illustration of a section through human skin affected by eczema, a skin inflammation characterised by itchy pink scales. Some of the epidermal cells (pink layer, upper frame) have broken down to form large yellow vesicles containing inflammatory cells. These vesicles can rupture onto the skin's surface to form crusts. At centre right is a hair (brown), and a sweat pore opening at centre left. The dermis (pale pink layer, bottom) has sweat glands (orange spirals), nerve fibres (yellow) leading to nerve endings (green), veins (blue) and arteries (red). White blood cells (with purple nuclei, centre) are leaving the arteries. While eczema may be due to an allergy, sometimes it has no obvious cause.