Moles Halo Nevi
Halo nevi occur primarily during adolescence. The average age of onset is 15 years. The incidence in the population is estimated to be 1%. Most halo nevi are located on the trunk; they never occur on palms and soles. They may occur as an isolated phenomenon or several nevi may spontaneously develop halos. A pre-existing nevus develops a surrounding rim of hypopigmentation that heralds the gradual disappearance of the nevus over several months. The depigmented halo is symmetric and round or oval with a sharply demarcated border. Skin biopsy shows a junction or compound nevus surrounded by a dense infiltrate of lymphocytes. There are no melanocytes in the halo area. Halo nevi appear to be a host response directed against the nevus cells. Focal atypical nevus cells may be seen though the majority of the pre-existing nevi are benign. The halo usually re-pigments over a few years. Woods light accentuates the halo. Halo nevi also occur in people with vitiligo. A halo may rarely develop around malignant melanoma, but in such instances it is usually not symmetric. People with halo nevi should have a full skin examination to look for vitiligo and also to screen for melanoma. Removal of a halo nevus is unnecessary unless the nevus itself has atypical features. Parental concern over this impressive change is often reason for a conservative excision. In such cases, the mole part of a halo nevus may be removed by shave or excision.