We report on a patient developing simultaneous occurrence of lentigo maligna lesions, solar lentigines and an extensive melanosis of the oral mucosa. Diagnostically, epiluminescence microscopy had a relevant role in the preoperative assessment and selection of suspicious pigmented lesions, as the lesions histologically labelled as lentigo maligna and solar lentigo were clinically indistinguishable. We review the clinical, dermoscopic and histopathologic differential diagnosis of solar lentigo, malignant lentigo and mucosal melanosis with other melanocytic and keratinocytic lesions and discuss the possible relationship between these entities.