title: 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.
authors.affiliation: Department of Pathology, Women's College Hospital, University of Toronto, Ontario, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Akasu
authors.forename: L
authors.initials: L
authors.lastname: From
authors.forename: H J
authors.initials: HJ
authors.lastname: Kahn
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016131:Lymphocyte Subsets; D008264:Macrophages / Q000145:classification*; D008297:Male; D009508:Nevus, Pigmented / Q000473:pathology*; D012867:Skin / Q000473:pathology; D012878:Skin Neoplasms / Q000473:pathology*