Large pigmented naevus (birthmark) on a young woman's calf. Naevi occur in different forms. Some are composed of small blood vessels (haemangioma), including the strawberry mark (which usually disappears in early life) and the port-wine stain (which does not disappear but may be treated with laser techniques). Moles are another kind of naevus, consisting of small, heavily pigmented regions of skin occurring all over the body surface.