What are Halo Nevi

Onset: occur primarily during adolescence. The average age of onset is 15 years.
Course: The halo usually re-pigments over a few years. Focal atypical nevus cells may be seen though the majority of the pre-existing nevi are benign.
Prevalence: 1% of the population
Site: located on the trunk; they never occur on palms and soles.
Appearance: The depigmented halo is symmetric and round or oval with a sharply demarcated border.
Development: Primary: may occur as an isolated phenomenon or Secondary: 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.
Significance: Halo nevi appear to be a host response directed against the nevus cells.
Associated Lesions: 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.
Implications: People with halo nevi should have a full skin examination to look for vitiligo and also to screen for melanoma.
Diagnosis: Woods light accentuates the halo. Skin biopsy shows a junction or compound nevus surrounded by a dense infiltrate of lymphocytes. There are no melanocytes in the halo area.
Treatment: Removal of a halo nevus is unnecessary. If the nevus itself has atypical features, a conservative excision in which the mole part of a halo nevus may be removed by shave or excision.















A halo around a malignant melanoma