Derm Dx: Hypopigmented Lesion With Vanishing Mole

Halo nevusA halo nevus is a rare benign dermatologic entity characterized by a typical whitish rim encircling the existing melanocytic nevus resembling a halo.1 In 1916, Sutton clinically described 3 such lesions as "leukoderma acquisitum centrifugum."2 Therefore, Sutton is widely...

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Halo nevus

A halo nevus is a rare benign dermatologic entity characterized by a typical whitish rim encircling the existing melanocytic nevus resembling a halo.¹ In 1916, Sutton clinically described 3 such lesions as “leukoderma acquisitum centrifugum.”² Therefore, Sutton is widely credited for describing halo  nevus.³ In Borroni and Vignati’s article highlighting the history of halo nevus, Kaposi actually gave Hebra credit for being the first to accurately describe a halo nevus in the literature.⁴ Happle also suggested that the alternative term, “Grunewald nevus,” was more appropriate than the term “Sutton nevus.”² It is now well accepted that the inflammatory response seen in a halo nevus is mostly lymphocytic in nature, often with a small number of melanophages.⁵

Clinically, patients may start to notice an area of erythema or redness around a nevus.  This area of erythema then starts to depigment, leaving a halo of white skin around the nevus.  Occasionally, over time the original nevus (in the center of the white halo) may start to lighten and even disappear (thus possibly leaving a depigmented circle). 

Halo nevi are reported to occur in approximately 1% of the population and are most commonly located on the trunk; however, they may appear in multiple locations.⁶ Both genders are equally affected, and most halo nevi appear during an individual’s teenage or young adult years.⁶ There is no predilection for race.⁶

The natural history of halo nevi is not well understood, but there have been reported cases of patients with a history of congenital halo nevi or vitiligo, which suggests a possible link. The relation between halo nevi and vitiligo remains unclear, but the two diseases do share a common pathologic end point — the destruction of normal melanocytes. Additionally, both of these pathologies are associated with antimelanocyte tumor responses.⁷ One case by Kawaguchi et al described a patient with multiple halo nevi after a short period of sunbathing, which suggested a possible relationship between sun exposure and halo nevi development.⁸ The onset of multiple halo nevi has also been noted to occur after treatment with various immunotherapies including interferon-alfa, infliximab, imatinib, and tocilizumab.⁸

Halo nevi are more commonly linked with benign melanocytic nevi, but rarely they can occur within nevi with various degrees of atypia, in nonmelanocytic tumors, in inflammatory lesions, and in melanoma. A band-like lymphohistiocytic infiltrate in the dermis is the characteristic histopathologic feature.⁹ Halo nevi usually persist for a decade or longer, and education about the prolonged history may be necessary to reassure patients about the benign nature of the lesion and to avoid unnecessary excisions.¹⁰ Traditionally, halo nevi have been clinically described as dysplastic lesions; however, the presence of dysplasia has not been found on histologic examination.¹⁰ 

In 1974, after performing a series of ultrasound studies, Hashimoto suggested that autophagocytosis of melanosomes in halo nevi was responsible for the depigmentation that is observed clinically.¹¹ At the time of his experiments, Hashimoto was unsure whether the lymphocytic infiltration seen in halo nevi played a primary or secondary role in the early stages of the nevus’ development.¹¹ In 1999, Musette et al hypothesized that halo nevi were caused by an autoimmune-like response.¹² While there have been many proposed etiologies, the exact pathophysiology leading to the development of a halo nevus has still not been clearly delineated. However, it has been widely accepted that cell-mediated immunity plays a primary role in pathogenesis.¹³

Granulomatous inflammation has been found on histologic examination of halo nevi, but this finding was only reported in those lesions that occurred with cysts, folliculitis, or trauma, and it was also noted that the presence of this inflammation was not a primary response to a halo nevus but rather secondary to an underlying event.¹⁴ Additionally, some have suggested that one possible explanation for the granulomatous inflammation seen in some halo nevi is the coexistence of a systemic granulomatous disease, such as an infectious process caused by atypical mycobacteria or sarcoidosis.¹⁵ In halo nevi going through regression, granulomatous inflammation may occur due to an exaggerated cell-mediated immune response; T lymphocytes may produce lymphokines excessively, which could then act as an attractant for large numbers of macrophages with an activated phenotype.¹⁵ As is evident from the description above, there are multiple potential causes underlying the presence of granulomatous inflammation seen in some cases of halo nevi, and practitioners must look out for other pathology that could contribute to this finding.

When considering a diagnosis of halo nevus, one must also include melanoma in the differential. Despite the fact that halo nevi are very rarely associated with melanoma, the central lesions should be evaluated and biopsied if any diagnostic uncertainty exists.¹⁶ Halo nevi can also at times be similar in presentation to vitiligo, and it is important to differentiate the two in these cases. An example where the differentiation between the 2 diagnoses has been at times challenging is in patients with Turner syndrome. These patients have been reported to have an increased prevalence of halo nevi rather than the sometimes misdiagnosed vitiligo.¹⁷ Lastly, dysplastic nevus should also be included in the differential diagnosis when evaluating a patient with a suspected halo nevus.¹⁰

The treatment for halo nevi has proven to be somewhat controversial. Because of the fact that halo nevi are suspected to arise from nevus cells that are atypical or going through malignant transformation, some may choose to treat these aggressively. However, this suspicion has yet to be proven and therefore leaves room for physician discretion in the treatment plan.⁷ The current recommendations for the management of halo nevi are broad, ranging from observation without intervention to excisional biopsy.⁷ Treatment plans may also be guided by cosmetic concerns that the patient might have. For example, many patients in Asian countries are concerned about the cosmetic effects of the hypopigmentation surrounding the lesion, especially when located on the face.⁷

For the patient described in this case, the lesion had not been changing for several months. Therefore, the physician decided to monitor the lesion rather than perform a biopsy. The patient was given the option to excise the lesion if it was displeasing to her cosmetically, but she instead elected to continue with yearly observation.

Jessica Sheu, BA is a medical student, Joan Fernandez is a medical student, and Christopher Rizk, MD, is a dermatology resident at the Baylor College of Medicine in Houston.

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17. Brazzelli V, Larizza D, Martinetti M, et al . Halo nevus, rather than vitiligo, is a typical dermatologic finding of Turner’s syndrome: clinical, genetic, and immunogenetic study in 72 patients. J Am Acad Dermatol. 2004;51:354-358.