5.1.3　Lentigo maligna melanoma

Lentigo maligna melanoma is a type of invasive skin cancer.It develops from lentigo maligna，which is sometimes called Hutchinson's melanotic freckle.Lentigo maligna stays on the outer surface of the skin.When it starts growing beneath the skin's surface，it becomes lentigo maligna melanoma.It's the least common type of melanoma.Lentigo maligna grows slowly and is usually harmless，but lentigo maligna melanoma can spread aggressively.It is important to recognize the symptoms of lentigo maligna melanoma in the early stage.Histopathological manifestations are the proliferation of heterotypic melanocytes in the basal layer of the epidermis，and the appearance of melanocyte lesions on the face observed by dermoscope is different from other parts.Stolz et al.took the lead in observing lentigo maligna melanoma on face with dermoscope，and summarized the characteristic manifestations at four stages：stage Ⅰ，the appearance of asymmetric follicular openings with hyperpigmentation indicates that the melanoma cells descend unevenly toward a single hair follicle；stage Ⅱ，short and thin stripes，dots and globules appear around the follicular opening，exhibiting a circular granular pattern；stageⅢ，as the stripes around the follicular opening become longer and intersect，a diamond-shaped pigmentation is gradually formed；stage Ⅳ，as the melanoma cells inside the follicle expand，the pigmentation begins to merge until the follicular opening disappears.The sensitivity and specificity of this model for the diagnosis of lentigo maligna melanoma are 89％and 93％，respectively.This model can be used for clinical diagnosis and follow-up to observe the progress of lentigo maligna melanoma.

Overall，dermoscope has an irreplaceable role in assessing skin tumors because it has significantly improved the performance of dermatologists.In addition，with the continuous improvement of the appearance and mode of dermatosis upon dermoscope，dermoscope has gradually played a role similar to a pathologist's stethoscope.(https://www.daowen.com)