Description

Halo nevus is an ordinary benign melanocytic nevus in the process of regression often seen with a depigmented or targetoid halo. It usually occurs in the 1st or 2nd decade of life and can occur anywhere on the body. The lesion consists of a sharply defined depigmented area surrounding a nevus. Although the central nevus usually disappears over a period of several months to years, the halo may or may not disappear. The halo appears to be an immune response to the melanocytes in the dermal–epidermal junction. In 1969, Sutton called this lesion leukoderma acquisitum centrifugum and considered it to be a form of vitiligo (1).

Epidemiology

• Halo nevi are uncommon; they affect fewer than 200,000 people in the U.S. population.
• Occurs in both sexes and in all races
• More often seen in teens, children, or young adults
• Most often is located on the upper back
• Can occur spontaneously or in patients with vitiligo (18–26%)
• Can last a decade or longer
• May develop around a congenital melanocytic nevus or a nodular melanoma

Etiology and Pathophysiology

• Biopsy shows junctional dermal or compound nevus surrounded by lymphocytic infiltrate.
• Nevus cells undergo apoptosis and disappear.
• Considered to be both humoral and cellular immunologic phenomenon
• The infiltrating cells are predominantly T lymphocytes, and cytotoxic (CD8) lymphocytes outnumber helper (CD4) lymphocytes by a ratio of ~4:1.
• Decrease or total absence of melanin and melanocytes in the halo
• Stages of halo nevi
  • Not all halo nevi evolve through each stage, but many do and exhibit characteristic signs (2).
  • Stage I—when the central nevus remains brown in color (classic form of halo nevus) (2)
  • Stage II—when the pigmented central nevus starts to disappear leading to a pink papule (2)
  • Stage III—when the pigmented central nevus may disappear completely, leading to a circular area of depigmentation (2)
  • Stage IV—the depigmented area may repigment leaving no evidence of its existence (2).

Risk Factors

• Family history of vitiligo
• Family history of halo nevi

Commonly Associated Conditions

Vitiligo (26% of cases)