Synonyms: Sutton's naevus, leukoderma acquisita centrifugum.

Description

This 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 its sufferers 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.¹

Visual appearance

Epidemiology

They are common lesions and estimated to have a prevalence in the general population of about 1% in the US.¹ Turner's syndrome patients have a higher prevalence of halo naevi than the general population.² Some families may have a tendency to the lesions.¹

Presentation

• Halo naevi most commonly affect younger people and the average age of onset is about 15 years.¹
• They are usually asymptomatic lesions, apart from the cosmetic disturbance that they cause.
• The central naevus may involute and then subsequently repigment, over a period of years.
• There may be occasional inflammatory crusting within the depigmented zone.
• The lesion may be solitary but may occur as multiples on occasion.
• They are most commonly found on the trunk but can occur at any site.
• They usually consist of a central uniformly pigmented naevus, usually round or oval in shape, with a surrounding area of depigmentation of uniform width from the naevus's edge.
• Where the naevus has undergone involution there may just be an isolated white circular/oval macule.

Differential diagnosis

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

• None are 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.³
• 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's syndrome²
• Vitiligo⁴

Management

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.⁵ If the area of depigmentation is large this may lead to requests for cosmetic attention. Various techniques are reported, including tattooing⁶ and topical tacrolimus.

Complications

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

Prognosis

Excellent.