This study investigates the efficacy of photodynamic therapy (PDT) in the treatment of lentigo maligna (LM). Hyperspectral imaging system (HIS) will be used to determine the margins of LM and to rule out possible invasion. Participants will receive photodynamic therapy three times consecutively with intervals of two weeks using 5-aminolevulinic acid nanoemulsion (BF-200 ALA, Ameluz®) as a light sensitizing cream. Four weeks after last photodynamic therapy the lentigo maligna lesion will be excised surgically from the skin. Result of the treatment is assessed with histopathological examination and immunohistochemical staining of removed tissue specimen.