A complex immune response in halo nevi correlates with immune reactivity on infiltrated melanocytes, adjacent hair follicles and blood vessels

Ana Maria Abreu Velez,Michael S Howard,Vickie M Brown

doi:10.7241/ourd.20144.70

Abstract

Introduction: A clinical is a benign melanocytic-neoplasm, often exhibiting spontaneous involution. A characteristic clinical feature is depigmentation of the surrounding skin, and a centripetal progression of the tumor regression phenomenon. Case Report: An 18 year old male consulted the dermatologist for changes in color of an asymptomatic mole. Materials and Methods: A clinical evaluation was performed, and skin biopsies were obtained for hematoxylin and eosin (H&E) review, and for immunohistochemical (IHC) studies including CD3, CD4, CD8, CD20, CD68, CD99, myeloid/histiocyte antigen, S-100, PNL2 and SOX- 10. Results: A neoplastic process was identified on H&E examination, located along the dermal/epidermal junction and within the dermis. The neoplasm was composed of nests, cords and strands of benign melanocytes, with infiltrating lymphocytes. IHC staining demonstrated a strong pattern of positivity with all of the IHC antibodies within, infiltrating and surrounding the primary neoplastic process. In addition, evidence of the primary tumor immune response was noted around surrounding blood vessels and hair follicles, and on adjacent epidermal melanocytes. Conclusions: In the present study, we demonstrate by histopathologic and immunologic evidence that lymphocytes are primarily responsible for halo nevus tumor regression. Moreover, the immune response involves not only CD8 positive T lymphocytes, but a larger spectrum of B and T lineage lymphocytes. Thus, the immunologic foundations of halo nevus regression are likely of greater complexity than previously determined.

Highlights

A clinical “halo nevus” is a benign melanocytic-neoplasm, often exhibiting spontaneous involution
A band-like, lichenoid infiltrate of lymphocytes and histiocytes was present immediately subjacent to the lesion, and infiltrating some of the lesional melanocytes (Fig. 1)
The halo nevus immune response has been previously regarded as an autoimmune process, mediated primarily by CD8 positive T lymphocytes

Summary

Introduction

A clinical “halo nevus” is a benign melanocytic-neoplasm, often exhibiting spontaneous involution. A characteristic clinical feature is depigmentation of the surrounding skin, and a centripetal progression of the tumor regression phenomenon. IHC staining demonstrated a strong pattern of positivity with all of the IHC antibodies within, infiltrating and surrounding the primary neoplastic process. Evidence of the primary tumor immune response was noted around surrounding blood vessels and hair follicles, and on adjacent epidermal melanocytes. Conclusions: In the present study, we demonstrate by histopathologic and immunologic evidence that lymphocytes are primarily responsible for halo nevus tumor regression. The formation of the halo is thought to occur when certain CD8 positive T lymphocytes appear in a lichenoid band below the nevus and destroy the melanocytes. The current medical literature suggests that if there is a change in appearance, or the halo nevus becomes painful, itchy, or infected, a physician should be consulted [1,2,3,4,5]

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Results

Conclusion