Lentigo maligna: a review.

Lentigo maligna (LM) is a melanoma in situ with distinct clinical features and histology. It commonly affects males after the sixth decade of life. Incidence rates of LM have increased based on early 21st century data from different countries, however data are suboptimal. Data from England show a plateauing crude incidence between 2013-2019. By comparison, invasive melanoma and other types of melanoma in situ commonly appears in younger age groups (median age 58 and 67 years old, respectively) and incidence is rising. The most important risk factors for LM include fair skin and cumulative ultraviolet solar radiation exposure. Although LM is limited to the epidermis and connected skin adnexa, it may progress to invasive lentigo maligna melanoma. The reported rate of malignant progression varies, reflecting a challenge for LM epidemiology research, as often lesions are removed on diagnosis. LM poses a challenge in diagnosis and management. While it can be diagnosed clinically or dermoscopically, the gold standard remains histopathological assessment of biopsied skin tissue. Reflectance confocal microscopy allows for better appreciation of the complexity of LM at a cellular level, often progressing beyond clinical margins. Management of LM may involve Mohs micrographic surgery or excision, although recurrence may occur even with 5 mm clinical margins. Imiquimod cream may be effective, but incomplete treatment and recurrence has been reported. Conservative management with observation or radiotherapy may be used in selected cases. 5-year net survival rates are excellent. This paper reviews the natural history, epidemiology, aetiology, pathogenesis, diagnosis and management of LM.