Halo nevus is a pigmented nevus surrounded on the periphery by a patch of discolored skin similar to vitiligo. It can be singular and plural. In the diagnosis of halo nevus, the main one is its differentiation from those forms of melanoma that are accompanied by depigmentation along the periphery of the formation. Dermatoscopy, syascopy and nevus biopsy are performed. With confidence in the diagnosis of halo nevus, treatment is not required. Education often regresses on its own. If melanoma is suspected, surgical excision of the nevus, including the depigmentation zone, is necessary.
Halo nevus occurs in people of both sexes and of any age category, but more often in children and in adolescence. It is diagnosed in about a quarter of patients with vitiligo, as well as in people prone to autoimmune diseases. Sometimes the appearance of nevus occurs before the development of vitiligo and is found in the sisters and brothers of a patient with vitiligo.
Some authors engaged in research in the field of dermatology note that halo nevus is a skin reaction to exposure to increased ultraviolet radiation and develops against the background of atopic sunburn. An autoimmune mechanism of the development of education is also assumed, since cytotoxic antibodies are detected in the blood of such patients. Due to the presence of the depigmentation rim, the names halonevus (halos, halo – circle) and perinevus vitiligo have become synonyms of nevus Setton.
When a Setton nevus occurs, a pigmented nevus first appears, and then a rim of depigmented skin forms around it. In some cases, depigmentation may be preceded by a slight redness. The nevus itself is a red-brown, milky-brown or brown nodule, slightly rising above the general level of the skin. It has a rounded shape and clear borders. The discoloration area is usually 2-3 times wider than the pigment formation located in its center.
Halo nevus is most often located on the skin of the trunk and upper extremities, less often on the face. As a rule, these are multiple formations. One patient may have up to 100 nevi. In rare cases, Halo nevus is isolated. Halo nevus refers to melanomoneurophic nevi and is prone to gradual spontaneous disappearance. However, according to some data, it can be associated with melanoma, neurofibromatosis, malignant tumors of internal organs.
The most characteristic and distinctive symptom of halo nevus is its stage development: the appearance of a pigmented formation, after a few months the appearance of a hypopigmentation or discoloration area around it, then a regression of the pigmented part of the nevus for several years and only after that a gradual staining of the depigmented rim to the color of normal skin.
The typical clinical picture and the stage of development in many cases make it possible to make a diagnosis without difficulty. Difficulties in diagnosis arise when a nevus appears against the background of existing vitiligo. To clarify the diagnosis, dermatoscopy and syascopy are performed, which reveal clusters of nevus cells surrounded by infiltrate of lymphocytes in the center of formation, and the absence of melanocytes in the epidermis in the area of the depigmented rim.
The similarity of some forms of melanoma with halo nevus makes it necessary to consult a dermatologist. In some cases of melanoma, there may be a discolored rim around the pigment center and a regression of pigmentation is possible. These signs make melanoma very similar to halo nevus. Therefore, to exclude it, a biopsy of the formation and subsequent histological examination of the sample can be carried out. In addition, differential diagnosis of halo nevus with neurofibroma, vulgar wart, vitiligo, blue nevus is carried out.
Patients with halo nevus are shown to be monitored by a dermatologist until signs of regress of education appear. It is recommended to avoid increased ultraviolet radiation (natural and in a solarium), use professional protective equipment with SPF 50.
Treatment is carried out in cases where it is impossible to clearly differentiate nevus from melanoma. At the same time, a complete surgical excision of the nevus along with a depigmented rim is shown.