Lentigo maligna (LM) is a type of melanocytic proliferation, the term being used by clinicians and pathologists for melanoma in situ on chronically sun damaged skin (1) in case that the lesion is confined to the epidermis. The pathology in question is classified as lentigo maligna melanoma (LMM) when it invades the dermis (2), over a protracted period of time (3). They both represent a subtype of malignant melanocytic proliferation according to the World Health Organization criteria (4). Once the dermis is invaded, the prognosis of the lesion is similar to that specific for other types of melanoma (5). Most LM patients display a slowly enlarging pigmented macula or patch which tends to occur in middle aged and older individuals (6), with a slight female preponderance (2).
The preferred method for diagnosing LM is excision (7), secondary to dermatoscopy (8) and biopsy (9). Distinguishing LM from a background of increased melanocytes on chronically sun damaged skin in a small biopsy specimen remains one of the most serious diagnostic challenges for dermatopathologists (10). Histology shows proliferation of atypical melanocytes at the epidermal-dermal junction in small nests or single cells (11).