Halo Naevus

Synonyms: Sutton's naevus, leukoderma acquisita centrifugum

What causes halo naevus?^{[1, 2]}

A halo naevus is a benign skin lesion that is a result of a common melanocytic naevus undergoing an inflammatory process, such that a zone of depigmentation surrounds the mole. There is an infiltration of T lymphocytes and macrophages and possibly some antibody-mediated autoimmunity. The aetiology and pathophysiology of the immune reaction to the presence of an aggregate of melanocytes is poorly understood.

The lesion can cause significant anxiety in those who have it, due to its characteristic and striking appearance. The central naevus may undergo involution leaving a grey or white halo that can resemble melanoma that has undergone regression, leaving the clinician with a diagnostic dilemma on occasions.

How common is halo naevus?

They are common lesions and estimated to have a prevalence of about 1% in the general population.^[3] Turner syndrome patients have a higher prevalence of halo naevi than the general population.^[4] Some families may have a tendency to the lesions. Halo naevi most commonly affect younger people and the average age of onset is about 15 years.^[5]

Halo naevus symptoms^{[2, 6]}

Halo naevus

By JeffyP, Public domain, via Wikimedia Commons

• They are usually asymptomatic lesions, apart from the cosmetic disturbance that they cause.
• A solitary halo naevus or multiple halo naevi are most often found on the trunk. They are less common on the head and are rare on the limbs. Halo naevi may follow the Köbner phenomenon, arising within a mole that has been injured in some way.
• The white halo is usually about 0.5-1.0 cm wide and is symmetrical (round or oval in shape). The halos develop at intervals round one or several moles, but not around all of them.
• There are four stages of a halo naevus. It may take several years to complete the cycle. Multiple halo naevi can be at different stages:
• Stage 1: A rim of pale skin surrounds a mole.
• Stage 2: The mole may become pinker or less pigmented, and fades away.
• Stage 3: A circular or oval area of depigmentation persists.
• Stage 4: The affected skin gradually returns to its normal colour.
• The central naevus may involute and then subsequently repigment, over a period of up to ten years.^[7]

Differential diagnosis^{[2, 6]}

The lesion has a characteristic appearance that usually means it is not confused with other diagnoses. The following problems can present with a similar appearance and should be considered as the cause of a depigmented lesion but should usually be able to be discriminated on the grounds of their history or appearance:

• Lichen planus.
• Basal cell carcinoma.
• Lichen sclerosus et atrophicus.
• Tinea corporis.
• Vitiligo.
• Malignant melanoma.
• Molluscum contagiosum.
• Pityriasis versicolor.
• Dysplastic naevus.
• Hypopigmented skin lesion of sarcoidosis.
• Verruca.

Investigations^{[2, 6]}

• None is required if the lesion has a typical history and appearance.
• A Wood's light may be used to distinguish diagnoses such as tinea/pityriasis versicolor.
• Dermoscopy may be used to demonstrate characteristic patterns of pigmentation associated with benign melanocytic naevi.^[6]
• If there is any uncertainty as to the nature of the lesion, consider dermatological referral or excision biopsy to exclude melanoma.
• Features that would prompt the need for excision biopsy include:
  • Irregularity of the margin of the pigmented or depigmented zones.
  • Non-uniformity of overall shape.
  • Papular component that is not centrally located.
  • Rapid growth of the lesion.
  • Rapid increase in pigmentation of the pigmented zone.
  • Irritation, bleeding or ulceration of the lesion.

Associated diseases

• Turner syndrome.^[4]
• Vitiligo.^[8]
• Halo naevi-associated leukoderma.^[9]

Halo naevus treatment

Halo naevi are benign lesions that require no active management other than reassurance of the patient. Sometimes treatment for cosmetic reasons may be requested. The depigmentation can be particularly noticeable in darker-skinned individuals.

Other than excision, laser treatment has been used.^[10] If the area of depigmentation is large, this may lead to requests for cosmetic attention. Various techniques are reported, including tattooing and topical tacrolimus.^[11]

Complications

There are no complications as such, unless the lesion is misdiagnosed or there are problems associated with excision biopsy.

Prognosis

The lesion is benign so the prognosis is excellent.