Track

Case Reports

Abstract

Poliosis is a condition in which a patch of white hair occurs while the rest of the hair color remains normal which can happen in various conditions. A halo nevus (HN) is a benign melanocytic nevus surrounded by a depigmented ring. HNs typically do not appear on the scalp. We are reporting a case of a 9-year-old girl who suddenly developed white hair on her scalp. The biopsy showed a regressed nevus with exuberant T-cell infiltration, including a relatively high percentage of CD8+  T cells. The parents reported a nearby congenital nevus. The mononuclear cell infiltration was found in close contact with melanocytes, and these melanocytes showed signs of cellular damage, resulting in depigmentation. This patient displays one of the rare cases of an unusual presentation of a halo nevus on the scalp with poliosis. The main hypothesis is based on a theory of a cellular immune response targeting the pigmented cells and subsequent appearance of abnormal melanocytes around the HN. We believe the poliosis within the HN follows the same cellular immune response as vitiligo, targeting the melanocytes and leading to the subsequent appearance of abnormal melanocytes. We hope our case provides further insight into the presentation of immunological mechanisms behind hypopigmented cutaneous lesions such as HN, poliosis, vitiligo, and alopecia. Although rare, the phenomenon of halos can develop spontaneously around congenital nevi, representing a sudden change in hair color near a nevus that has been present for years.