Background: Lentigo maligna often presents as a slowly growing pigmented macule or patch that develops on chronically sun-damaged skin. It is melanoma in-situ and can become quite extensive and progress to invasive melanoma if left untreated. Interestingly, Lentigo maligna has occasionally been noted to have the capacity to invade and re-pigment gray or white hair.
Methods: A retrospective case review was performed of patient's history.
Results: A 79-year-old male who previously had white scalp hair presents with a patch of brown hair on the vertex of the scalp. At age 8 the patient had had previous radiotherapy to the site for the treatment of tinea capitis. Histology showed lentigo maligna type melanoma in-situ with high- and low-density areas and marked adnexal colonisation including extension into the germative portion of the hair follicle. The patient underwent surgical excision with a split thickness skin graft.
Conclusion: This case highlights one feature that should raise suspicion for melanoma on the scalp - the rare phenomenon of re-pigmentation of previously white or fair hair. This phenomenon is the reverse of poliosis. It also showcases a potential contributing factor of past scalp radiotherapy as a risk factor in the development of melanoma.