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Precancerous limited Dubreuil melanosis: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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Precancerous limited Duobreille melanosis (blue lentigo maligna Hutchinson) is a disease that belongs to the group of precancerous conditions. The classical manifestation of Dyubreil's melanosis in places exposed to insolation (on the face, especially often in the zygomatic area), is characterized by spots with irregular polycyclic outlines. Slowly and unevenly increasing, the color of which varies from light coffee to dark brown or black. The color unevenness is characteristic: on the one hand, presence of separate pigmented zones on the background of less intensively colored areas, on the other hand, along with sharply pigmented areas of black color, there are spots of bleaching and even depigmentation during spontaneous regression of some areas. There are also amelanotic forms of precancerous melanosis. The onset of invasive growth is accompanied by the consolidation of individual areas, which acquire a nodular character, the surface becomes papillomatous, the peeling increases and erosion may occur.
Pathomorphology. In the basal parts of the epidermis, proliferation of atypical melanonites with long processes, often taking a spindle-shaped shape, is revealed. The cytoplasm of atypical melanocytes is vacuolated, the nuclei are hyperchromic, with pronounced polymorphism. With the progression of the disease, atypical melanocytes are grouped into nests, often oriented parallel to the surface of the epithelium. There are multinucleated melanocytes. A large amount of melanin usually accumulates in the epidermis. Characteristically early involvement in the process of epithelium of hair follicles, where atypical melanocytes are located along the basal layer, in the form of a continuous network. The epidermis is atrophic. Melanophages, dystrophic changes of collagen, sometimes an inflammatory infiltrate from lymphocytes and plasma cells are found in the subepidermal sections of the dermis, which, however, is more characteristic for the onset of invasion (lentigo-melanoma).
Histogenesis. Electron microscopy does not detect specific changes in melanocytes in pre-malignant melanosis. They are large, have an active appearance and a large number of processes. Melanosomes are more elongated than those in normal skin melanocytes.
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