Blue nevus

Blue nevus (syn: blue nevus of Jadasson). Isolate the usual and cellular blue nevuses.

[1], [2], [3], [4], [5], [6]

Pathogenesis

In the usual blue nevus, spindle-shaped and process cells containing melanin in the form of large, well-distinguishable granules are revealed in the dermis, so that the outgrowth is contoured with greater magnification. Kernels can be poorly visible due to the abundance of pigment. There is no mitosis and atypism of cells. Cells are located rather randomly between collagen fibers, often at a great distance from each other, they can be very small; sometimes they are found in the walls of blood vessels and in nerve fibers. At the same time, there may be a slight proliferation of cells of the fibroblastic series.

Cellular blue nevus is characterized by a larger area, usually occupying the entire thickness of the mesh layer of the dermis, as a rule, has a characteristic configuration in the form of an hourglass - forms limited tumors in the dermis and subcutaneous tissue connected by a narrow isthmus. The nevus is formed mainly by spindle-shaped cells and is characterized by biphasic - alternation of cells with a light cytoplasm and strongly pigmented cells. Cell nuclei, as a rule, are monomorphic, without pronounced nucleoli or signs of atypism. Single mitosis can be observed. On the periphery, pigmented melanocytes with long processes are found. Indistinguishable from the cells of the usual blue nevus. It is believed that the presence of these cells is mandatory for the diagnosis of the cellular blue nevus.

[7], [8], [9], [10], [11], [12]

Symptoms of the blue nevus

They are benign intradermal melanocytic tumors with characteristic clinical and morphological manifestations. The blue-black color is caused by the optical effect and is associated with the deep arrangement of melanin in the dermis.

In typical cases, the usual blue nevus is a slightly elevated, symmetrical papule of blue-black color, with a smooth surface, smooth, but not always distinct contours. On average, the size of the nevus is from 4 mm to 1 cm. It occurs mainly on the face, back of the hands and back, in the sacral region, more often in newborns and young children. Cellular blue nevuses clinically resemble ordinary blue nevuses, the bowls develop at a young age, but are congenital, some time slowly increase in size, can reach several centimeters in diameter, then remain stable. Often significantly protrude above the surface of the skin. Notices and bleeding are not characteristic. Preferred localization is the lumbosacral region, head and neck. There are multiple eruptive blue nevi. Occasionally, cellular blue nevi can become malignant.

[13], [14], [15], [16], [17]

Diagnostics of the blue nevus

Immunomorphological examination of nevus cells gives a positive coloring on the antigens S-100 and HMB-45.

Heterogenetically close to blue nevuses intradermal melanocytic nevi Ota and Ito. They usually exist from birth, but sometimes pigmentation occurs only in early childhood. More common in women.

[18], [19], [20], [21], [22], [23]