Characterization of the mononuclear infiltrate involved in regression of halo nevi

Abstract

Halo nevi are characterized by progressive degeneration of nevus cells surrounded by a mononuclear cell infiltrate. We studied the morphological features of the nevus cells and the composition of the mononuclear cell infiltrate in 15 cases of halo nevi using immunohistochemical techniques and a battery of antibodies to different subsets of lymphocytes and histiocytes. Regression could be divided into four more or less identifiable stages, associated with different subsets of lymphocytes and monocyte-macrophage lineage cells. Stage I (preregression): nests of unremarkable nevus cells were surrounded by a moderate number of T lymphocytes (relatively small percentage of helper inducer T cells), occasional B cells and macrophages. Stage II (early regression): large number of T lymphocytes and FXIIIa-positive cells were in close contact with nevus cell clusters which showed ragged edges. Lysozyme-positive cells and epidermal Langerhans cells were mildly increased. Stage III (late regression): single nevomelanocytes showing mild atypia were present. Numerous T lymphocytes and macrophages positive for lysozyme, KP1 and/or FXIIIa were interspersed between the nevus cells. Increased numbers of epidermal Langerhans cells were present. Stage IV (complete regression): no nevus cells were observed and moderate numbers of T lymphocytes only remained. These results suggest that T cells, especially T-suppressor cells, and different subsets of macrophages participate in the regression of the nevi.

The natural history of halo nevi: A retrospective case series

“…and they have been postulated to have different pathogenic mechanisms. 12,14,31,32 Although the prevalence of vitiligo was higher than would be expected in the background population (3.75%), the number in our study was too small to draw conclusions. The differential diagnosis of HN must include melanoma.…”

“…,[12][13][14][15][16] Because of the sudden appearance of a halo and ''change'' related to HN regression, patients may present to the dermatologist fearing early malignant melanoma. If clinical features of melanoma are identified in the central lesion, excision is required.…”

Completely regressed primary cutaneous malignant melanoma with nodal and/or visceral metastases: A report of 5 cases and assessment of the literature and diagnostic criteria

“…55 It is believed that the infiltrate serves as a harbinger of regression, likely through cell-mediated cytotoxicity of CD8 1 lymphocytes. 56,57 Activated T lymphocytes, as well as antibodies to cytoplasmic components of melanocytes, have been demonstrated in patients with halo nevi. 58,59 …”

Unusual Halo Nevi – Darkening Rather than Lightening of the Central Nevus

“…During the formation and regression of halo nevi, infiltrates composed of T cells, in particular CD8+ cytotoxic suppressor cells, have been observed [16, 17]. In addition, circulating activated lymphocytes were seen in patients with halo nevi and their disappearance was documented following surgical resection [18].…”