Longitudinal melanonychia often misdiagnosed and confused with melanoma. Signs that need to be seen while examining this nail condition 1 Hutchinson sign : the extension of brown black pigmentation from the nail bed matrix Lentigo maligna Altmeyers Encyclopedia Department Dermatology Lentigo Maligna Melanoma: Overview, Etiology and Pathophysiology, Epidemiology Lentigo maligna Altmeyers Encyclopedia Department Dermatology Lentigo Maligna Melanoma Treatment & Management Point of Care StatPearls