Dubreuil’s melanosis is a pre—melanoma skin disease, which is a single pigment spot with uneven outlines, located on an open area of the skin. The color of the spot varies from light brown to black and may be different in different areas of the spot. In order to differentiate Dubreuil’s melanosis from other non-visible skin diseases, dermatoscopy, cytological examination of a smear-imprint of a skin neoplasm is performed. Since Dubreuil’s melanosis is often malignified and turns into melanoma, its complete surgical excision to healthy tissues is preferable in treatment; X-ray therapy is possible.
Dubreuil’s melanosis is a pigmented formation that is a borderline pre-melanoma lesion of the skin. It belongs to the number of melanoma-threatening nevi. Dubreuil’s melanosis develops, as a rule, in elderly people. According to some reports, this disease occurs in 3 people out of 1000 people over 50 years old. Various authors cite figures according to which melanomas developed from Dubreuil melanosis account for 10% to 33% of all skin melanomas. The frequency of transformation of the disease into melanoma is 35-40%, some authors have indicated a figure of 75%. The causes of malignant degeneration of Dubreuil melanosis are considered to be insolation, mechanical, chemical and other injuries of neoplasms.
The disease is a flat single pigment spot, the uneven edges of which resemble a geographical map. At the beginning of the disease, the spot usually has a light brown color and a diameter of 2-3 cm. Gradually, the growth of the spot and the darkening of its color are noted. As a result, the size of the lesion of the skin can reach 20 cm in diameter. The spot acquires an uneven color from brown to black with gray or bluish areas. On the surface of the spot, there may be areas with no staining corresponding to the zones of spontaneous regression of the disease.
The localization of Dubreuil’s melanosis is characterized by open skin areas, mainly the face (nose, cheeks, forehead) and neck. In this regard, some authors point to the connection of the occurrence of the disease with the patient’s chronic solar dermatitis.
During the transition of Dubreuil melanosis to melanoma, a seal with a papillomatous surface is detected on the area of the pigment spot, a change in the color of the spot occurs (darkening or lightening), the peeling process increases, redness occurs around the spot, and erosion may appear on its surface. The exact causes of melanosis malignancy have not been established. A certain role in this process is assigned to insolation and traumatization of the affected area of the skin.
Modern dermatology cannot use a biopsy of a skin formation to diagnose the transformation of Dubreuil melanosis into melanoma, since such a method of research can astimulate tumor growth and its dissemination. Therefore, cytological examination of the smear-imprint from the surface of the formation is used. Simple fingerprinting from the surface can be uninformative. For this reason, the dermatologist scratches the surface of the formation a little before taking a smear. The diagnostic criterion for the occurrence of melanoma skin cancer is the detection of atypical melanocytes in the fingerprint.
In view of the large percentage of malignancy of the disease, in the case of diagnosis of Dubreuil melanosis, radical excision of the entire area of the skin lesion up to healthy tissues should be carried out. At the same time, 1-2 cm of unchanged skin is captured along the entire perimeter of the spot. Given the localization of the process on the face, its removal sometimes presents a difficult task for the surgeon and requires the use of plastic surgery methods. With large spot sizes and associated difficulties, local exposure to X-rays can be used for its surgical excision, which often gives good results.