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A 17-year-old teenager has developed fuzzy pale rings around several moles over the summer, the moles were present for years,possibly since birth. There is a family history of skin cancer.
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»What's the diagnosis?
The term pseudo-halo nevus was originally used by Zakaudek in 2006 to describe the nevi on a patient with multiple uniformly pigmented nevi with surrounding hypopigmented rings on her abdomen.1 Based on physical findings, this patient was initially diagnosed as having halo nevi. However, she eventually revealed that she applied sunscreen only to her nevi rather than all of her exposed skin prior to swimming and sunbathing, in order to avoid developing melanoma.
The authors noted multiple nevi with similar features on the patient's trunk and extremities, and coined the diagnosis pseudo-halo nevus. Zakaudek stressed the need to make patients, particularly adolescents, understand the need for compulsive use of sunscreen and other protective measures to the entire skin surface to reduce the risk of skin cancer.1
On further questioning, our patient confessed to placing a round opaque sticker over her nevi on her left costal margin when outside in the sun or in the tanning salon, to minimize the risk of skin cancer. This resulted in the development of a pseudo-halo nevi. A complete skin examination revealed many symmetric nevi with uniform pigmentation, texture, and well-demarcated borders but no other pseudo-halo nevi.
Differential diagnosis: Halo nevus
Halo nevus (also known as Sutton's nevus or leukoderma aquisitum centrifugum) describes a pigmented nevus that develops a usually sharply demarcated hypopigmented and eventually depigmented surrounding ring. The nevus usually disappears over months to years, and the halo repigments over months to years.2
Halo nevi have been reported in about 1% of individuals between infancy and age 30. The prevalence increases to 18% to 26% in individuals with vitiligo.3 Brazzelli found that halo nevus was more prevalent in patients with Turner's syndrome.4 Halos have been reported surrounding congenital nevomelanocytic nevus, blue nevus, and Spitz nevus, as well as nonmelanocytic lesions such as dermatofibroma, neurofibroma, and verruca plana.3 A halo phenomenon may develop around melanoma and regressing melanoma, but the halos are often not uniform or well demarcated. The pigmented lesions, if still present, usually have atypical features.
The exact pathogensis of halo nevus is unknown. Zeff proposed that the halo nevus resulted from both cell-mediated and humoral-mediated immune responses. He postulated that maturing nevi release nevocellular antigens, causing B-cell and T-cell activation. Subsequently, CD8+ T cells specific for the nevocelluar antigens and nevus-specific antibody are generated, triggering further loss of pigment around the nevus.5
In summary, careful detective work is necessary to distinguish between halo and pseudo-halo nevi. Appropriate counseling regarding the need for total body protection from sun exposure should be emphasized. At her follow-up examination, our patient no longer had the pseudo-halo nevi on her left costal margin. But she demonstrated another area of hypopigmentation (in the shape of the Playboy bunny logo) on the left hip.
MS. GLICK is a medical student at George Washington University Medical School, Washington, DC.
DR. YAMOUT is a research fellow in the Division of Pediatric Surgery, Department of Surgery, School of Medicine and Biomedical Sciences, SUNY at Buffalo, N.Y.
DR. GLICK is Vice Chairman, Department of Surgery and Professor of Surgery, Pediatrics, and Obstetrics/Gynecology, School of Medicine and Biomedical Sciences, SUNY at Buffalo, N.Y.
The authors and section editor have nothing to disclose in regard to affiliations with, or financial interests in, any organization that may have an interest in any part of this article.
Vignettes are based on real cases which have been modified to allow the authors and editor to focus on key teaching points. Images may also be edited or substituted for teaching purposes.
1. Zaludek I, Moscarella E, Argenziano G: Artifactual "pseudo-halo nevi" secondary to sunscreen application. J Am Acad Dermatol 2006;54:1106
2. Kane KS, Ryder JB, Johnson RA, et al: Color Atlas and Synopsis of Pediatric Dermatology. New York: McGraw-Hill Companies, Inc; 2002:158
3. Wolff K, Johnson RA, Suurmond D: Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, 5th Edition. New York: McGraw-Hill Companies, Inc; 2005:170
4. 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
5. Zeff R, Frietag A, Grin C, et al: The immune response in halo hevi. J Am Acad Dermatol 1997;37:620