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Precancerous limited melanosis of Dubreuil: causes, symptoms, diagnosis, treatment
Medical expert of the article
Last reviewed: 07.07.2025
Precancerous limited melanosis of Dubreuil (syn. lentigo maligna Hutchinson) is a disease belonging to the group of precancerous conditions. The classic manifestation of Dubreuil's melanosis in places exposed to insolation (on the face, especially often in the malar region) is characterized by spots with irregular polycyclic outlines. slowly and unevenly increasing, the color of which fluctuates from light coffee to dark brown or black. Uneven coloring is characteristic: on the one hand, the presence of individual pigmented zones against the background of less intensely colored areas, on the other hand, along with sharply pigmented areas of black color, foci of lightening and even depigmentation are observed with spontaneous regression of some areas. There are also amelanotic forms of precancerous melanosis. The onset of invasive growth is accompanied by compaction of individual areas, which acquire a nodular character, the surface becomes papillomatous, peeling increases and erosion may occur.
Pathomorphology. In the basal sections of the epidermis, a proliferation of atypical melanocytes with long processes is detected, often taking a spindle shape. The cytoplasm of atypical melanocytes is vacuolated, the nuclei are hyperchromatic, with pronounced polymorphism. As the disease progresses, atypical melanocytes are grouped into nests, often oriented parallel to the surface of the epithelium. Multinuclear melanocytes are encountered. A large amount of melanin usually accumulates in the epidermis. Early involvement of the epithelium of hair follicles in the process is characteristic, where atypical melanocytes are located along the basal layer, in the form of a continuous network. The epidermis is atrophic. In the subepidermal parts of the dermis, melanophages, dystrophic changes in collagen, and sometimes an inflammatory infiltrate of lymphocytes and plasma cells are found, which, however, is more characteristic of the onset of invasion (lentigine melanoma).
Histogenesis. Electron microscopy does not reveal specific changes in melanocytes in precancerous melanosis. They are large, have an active appearance and a large number of processes. Melanosomes are more elongated compared to those in melanocytes of normal skin.
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