Acrofacial Vitiligo Following Halo Formation around Congenital Melanocytic Naevi.

Sir,

Halo nevi and vitiligo are fairly common conditions with a prevalence of 1% and 1–2%, respectively.[1] Halo formation is well described around acquired nevi, but halo formation around congenital melanocytic nevi (CMN) is much less common. Rarer still is the association of halo CMN with extralesional vitiligo.[2] We report a 9-year-old male who developed halo around CMN that was followed by extralesional vitiligo on lips and fingertips.

A 9-year-old boy was brought to us for the appearance of depigmented patches on lips and fingers for last 3 months that were gradually progressing. The parents also reported that for the last 6 months the child had started to develop lightening of a large, dark hairy mole that was present on the back since birth. The hair on the lesion had also turned white. They had also noticed a similar color change around two small moles on the neck at around the same time. Examination revealed a 7 cm × 5 cm oval, light brown elevated plaque on mid back studded with 1-3 mm papules. It was surrounded by a 10 mm depigmented halo all around the lesion [Figure 1a]. Lips and fingertips showed patchy depigmentation suggestive of acrofacial vitiligo [Figure 1b]. Two halo nevi sized 8 mm × 8 mm were also seen on either side of the neck [Figure 1c and d]. Biopsies were obtained from the central part of nevi on the back and the surrounding hypopigmented portion, and it revealed bundles of oval to spindle-shaped nevi cells intermixed with the abundant inflammatory infiltrate consisting mainly of lymphocytes [Figure 2a and b]. Positive immunohistochemical staining with MELAN A/MART 1 confirmed the presence of nevus cells in the dermal infiltrate [Figure 2c]. The hypopigmented part showed decrease pigmentation of basal cell layer along with the absence of nevus cells and the inflammatory cells [Figure 2d].

Figure 1

(a) A 7 cm × 5 cm oval, light brown elevated plaque on mid back studded with 1–3 mm papules with surrounding 10 mm depigmented halo. (b) Lips and fingertips showing patchy depigmentation suggestive of acrofacial vitiligo. (c and d) Two halo nevi sized 8 mm × 8 mm seen on either side of the neck

Figure 2

Photomicrograph showing: (a and b) Bundles of oval to spindle-shaped nevi cells intermixed with the abundant inflammatory infiltrate consisting mainly of lymphocytes (a: H and E, ×10, b: H and E, ×40). (c) Positive immunohistochemical staining with MELAN A/MART 1. (d) The hypopigmented part showing decrease pigmentation of basal cell layer along with absence of nevus cells and the inflammatory cells

Halo nevus represents a pigmented nevus surrounded by a depigmented zone, also known as leukoderma acquisitum centrifugum. First described by Sutton in 1916. It may develop around various types of neuroectodermal lesions such as nevocellular nevi, spindle nevi, epithelioid nevi, blue nevi, neurofibromas, and melanoma.[2] The back is the most common site.[3] Histologically, it is characterized by a dense inflammatory infiltrate invading the nevus cell nests and is therefore also referred to as inflammatory halo nevus.[4] Natural history of CMN varies. The lesion may remain stable or undergo complete regression.[2] Surgical excision may be attempted if the lesion is significantly irregular; its appearance is unstable characterized by a change in pigmentation, size or presence of ulceration; if the patient request removal due to cosmetic reasons.[5]

The relationship between halo nevi and vitiligo is intriguing. While for long it was believed that both share a common immunological mechanism of pigment destruction, recent studies point toward their separate pathogenic mechanism.[5] The support to the hypothesis comes from an observation made by Workman et al.[5] who reported a recurrence of vitiligo lesions after their initial regression on the complete removal of nevi. Other observations that support for different triggers for halo nevi and vitiligo are that while halo nevi always begin around a nevus, vitiligo rarely does so; a lymphocytic infiltrate is always present in halo nevus but is exceptional in lesions of vitiligo.[6]

While leucodermatous change around acquired nevi is not uncommon, very few cases of CMN have been reported with halo formation and subsequent development of extralesional vitiligo.[57] A series by Stierman et al.[2] reviewed nine new patients and ten already reported patients from the literature. All the nine patients with CMN were associated with the development of vitiligo either simultaneously, following or even preceding halo formation. Vitiligo in our patient developed 3 months after halo formation.

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