Lentigo Maligna & Lentigo Maligna Melanoma: Why so confusing?
Lentigo maligna is melanoma in situ (i.e. “pre-melanoma”) that occurs primarily on heavily sun-damaged skin of elderly individuals. It typically presents in the sixth and seventh decades of life. Although many non-operative treatments have been used in the past to treat Lentigo maligna (i.e. cryotherapy, radiation therapy, laser ablation), these treatments all seem to be associated with high recurrence rates.
Lentigo maligna melanoma is invasive melanoma that develops in an area of lentigo maligna. This represents advancement of lentigo maligna, whereby a new “vertical growth phase” has begun. Appropriate treatment consists of excision and staging. Although some physicians have used Moh’s micrographic surgery for these type of lesions, evaluation of pigmented melanocytic lesions like this using Moh’s (which is a unique type of frozen section analysis) have been associated with both high false-positive and high false-negative rates, around 20-50%. Many physicians agree that permanent-section analysis is the most sensitive for evaluating the subtle microscopic/histologic changes typical of these lesions.
Once complete excision of these lesions is confirmed by a pathologist, then reconstruction of the defect can be performed.