A Teenager With a Changing Mole on Her Back

AUTHORS:
Alexander K. C. Leung, MD
University of Calgary and pediatric consultant at the Alberta Children’s Hospital in Calgary, Alberta, Canada

Benjamin Barankin, MD
Toronto Dermatology Centre in Toronto, Ontario, Canada

CITATION:
Leung AKC, Barankin B. A teenager with a changing mole on her back. Consultant360. Published July 18, 2017. https://www.consultant360.com/articles/teenager-changing-mole-her-back

A 16-year-old girl presented with a “changing mole” on her right upper back. Several asymptomatic pigmented moles had been noted on her back when she was approximately 10 years of age. Two years ago, a white halo had developed surrounding one of the moles (the biggest one) on the right upper back. Over time, there had been an increase in size of the halo and a decrease in size and pigmentation of the encircled mole. The patient was otherwise in good health, and she had no history of using any topical agents over the lesion. She had no personal or family history of autoimmune disorders or melanoma.

PHYSICAL EXAMINATION

Physical examination revealed a faint pink-colored mole measuring 0.4 by 0.8 cm on the right upper back, surrounded by a depigmented, symmetric macule measuring 2 cm in diameter. There were several melanocytic nevi on the back, with one adjacent to the halo. There were no other cutaneous or systemic abnormalities.

WHAT’S YOUR DIAGNOSIS?

Answer on next page.

ANSWER: Halo nevus

Halo nevus, also known as leukoderma acquisitum centrifugum or Sutton nevus, refers to a benign, mostly acquired, melanocytic nevus surrounded by a rim of depigmentation, resembling a halo.^1,2 The condition was first described by Sutton in 1916 under the name leucoderma acquisitum centrifugum.³

EPIDEMIOLOGY

Although all skin colors are susceptible to the development of halo nevi, fair-skinned persons (phototypes 1, 2, and 3) are more commonly affected than are dark-skinned persons (phototypes 4, 5, and 6).^4,5 The incidence in the white population is estimated to be approximately 1%.^6,7 The condition is common in children and young adults, with a mean age at onset of 15 years.^2,6,7 The sex ratio is approximately equal.¹ Most cases are sporadic, but familial cases also have been described.^2,8

ETIOPATHOGENESIS

In the majority of cases, the cause is idiopathic.⁷ Sometimes, the condition may follow chronic exposure to ultraviolet radiation, especially after sunburn, topical application of bleaching agents, radiotherapy, subcutaneous interferon beta-1a therapy, and systemic administration of imatinib.^9-13 Individuals with Turner syndrome and autoimmune diseases such as Hashimoto thyroiditis, vitiligo, alopecia areata, and celiac disease are at increased risk.^4,7,14,15 An immune response mediated by cytotoxic CD8⁺ T lymphocytes plays an important role in the destruction of melanocytes in the halo nevus, resulting in the formation of the depigmented area.^6,16

HISTOPATHOLOGY

Histologic examination of a halo nevus typically reveals a bandlike lymphocytic infiltrate consisting mainly of T lymphocytes in the papillary dermis in the halo area, absence of nevus cells alongside the lymphocytic infiltrate, and nests of nevus cells centrally.^6,17

CLINICAL MANIFESTATIONS

Clinically, the halo nevus presents as a melanocytic nevus, often acquired, surrounded by a rim of depigmentation resembling a halo.⁶ The acquired melanocytic nevus can be intradermal, junctional, or compound.⁴ A minority of halo nevi develop from congenital melanocytic nevi.¹⁶ The halo is best visualized with a Wood lamp.⁷ The size of the nevus itself is highly variable and ranges from a few millimeters to several centimeters.⁴ The diameter of the halo usually ranges from 1 mm to several centimeters.⁴

The site of predilection is the trunk, especially the upper back.⁶ Less commonly, halo nevi are found on the head and neck, and rarely on the limbs, groin, and axillae.⁶ Halo nevi are asymptomatic and occur most often as a solitary lesion.¹⁸ Multiple lesions are uncommon unless they are associated with an autoimmune disease; the nevi may be clustered.^2,18,19

Over time, halo nevus undergoes specific changes.^17,19-21 The central nevus may remain brown in color—the classic form of halo nevus (stage 1) or its pigment can disappear leading to a pink-colored papule (stage 2).²⁰ Eventually, the central nevus may disappear, leading to a circular area of depigmentation (stage 3).²⁰ Finally, the depigmented area may repigment, leaving no trace of its existence. Not all halo nevi evolve through the last 3 stages, and they can halt their development at any stage.¹⁹

DIAGNOSIS

The diagnosis is a clinical one and can be aided by dermoscopy. Dermoscopy typically shows the following patterns: uniform globular pattern, cobblestone pattern, structureless nonpigmented pattern, structureless brown pattern, reticular pattern, and reticular pattern with blue granules with or without scarlike areas.¹⁸ A biopsy is usually not necessary unless there are atypical features such as asymmetry of the lesion, irregular border, color variegation, eccentric placement of the pigmented portion, or size of the lesion greater than 6 cm, which can suggest a possible regressing melanoma.²²

DIFFERENTIAL DIAGNOSIS

Differential diagnoses include blue nevus, Spitz nevus, dysplastic nevus, pityriasis lichenoides, dermatofibroma, neurofibroma, verruca vulgaris, molluscum contagiosum, mongolian spot, café au lait spot, seborrheic keratosis, histiocytoma, and a regressing melanoma.^7,16 The presence of a zone of hypopigmentation (halo) surrounding a variety of skin lesions is referred to as the halo phenomenon.^1,17

COMPLICATIONS AND PROGNOSIS

The nevus can be cosmetically unsightly and an esthetic concern if it occurs in an exposed area. Malignant transformation has not been reported in the pediatric age group.²² The prognosis is excellent. In a study of 49 patients with untreated halo nevi, 25 patients (51%) had no change in the halo or nevus after an average of 4.2 years; 7 patients (14.3%) demonstrated partial nevus regression with persistence of the halo after an average of 6.7 years, 2 patients (4.1%) demonstrated complete involution of the nevus with persistent halo depigmentation after an average of 7.7 years; 4 patients (8.2%) demonstrated complete nevus involution with some repigmentation of the halo after an average of 11.8 years, and 11 patients (22.4%) demonstrated complete resolution of the nevus with complete repigmentation of the halo after an average of 7.8 years.¹

MANAGEMENT

Halo nevi are benign and generally do not require any intervention.

REFERENCES:

1. Aouthmany M, Weinstein M, Zirwas MJ, Brodell RT. The natural history of halo nevi: a retrospective case series. J Am Acad Dermatol. 2012;67(4):582-586.
2. Kolm I, Di Stefani A, Hofman-Wellenhof R, et al. Dermoscopy patterns of halo nevi. Arch Dermatol. 2006;142(12):1627-1632.
3. Sutton RL. An unusual variety of vitiligo (leucoderma acquisitum centrifugum). J Cutan Dis Incl Syph. 1916;34:797-800.
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