Melanoma, Lentigo Maligna Type
Soheil Sam Dadras, MD, PhD
Nicole Carreau
Key Facts
Terminology
Indolent melanoma subtype that typically evolves slowly
Invasive melanoma, lentigo maligna type
Clinical Issues
Usually occurs on head and neck (sun-exposed regions) of elderly patients
Broad patch with irregular, mottled pigmentation and irregular borders
Microscopic Pathology
Confluence of atypical melanocytes replacing basilar keratinocytes forming a cleft
Epidermal atrophy and loss of rete ridges
Tumor cells extend along adnexal structures
Invasion of dermis by atypical cells, usually in nests &/or fascicles
Dermal component often shows spindle cell &/or desmoplastic melanoma features
 Clinical photograph of lentigo maligna melanoma on the nose of an elderly patient shows irregular pigmentation  . Both in situ and invasive melanoma were present on biopsy. (Courtesy P. Hsu, MD.) |
 LMM shows epidermal atrophy, consumed rete ridges, and an atypical junctional melanocytic lesion  . The papillary dermis is obscured by a dense lymphocytic infiltrate, but focal invasion is present  . |
TERMINOLOGY
Abbreviations
Lentigo maligna melanoma (LMM)
Synonyms
Invasive melanoma, lentigo maligna type
Hutchinson freckle (clinical term, which typically refers to melanoma in situ, lentigo maligna type)
Definitions
Indolent melanoma subtype that evolves slowly and usually presents on head and neck (sun-exposed regions) in older patients
CLINICAL ISSUES
Epidemiology
