Lentigo maligna melanoma. Light micrograph (LM). Lentigo maligna melanoma (LMM) is diagnosed when the melanoma cells have invaded into the dermis and deeper layers of skin. Lentigo maligna has a lower rate of transformation to invasive melanoma than the other forms of melanoma in situ (under 5% overall). However, the risk of invasive melanoma is greater in larger lesions, with up to 50% of those with diameter of greater than 4 cm being reported to have an invasive focus. Follicular involvement of lentigo maligna, (seen here) is considered a histopathologic hallmark. LMM occurs in sun damaged skin so is generally found on the face or neck, particularly the nose and cheek. Magnification: x 60 when printed at 10 centimetres high.