Nevus of Ota and Ito: causes, symptoms, diagnosis, treatment

Nevus of Ota is a skin hyperpigmentation area, solid or with small inclusions, from blue-black to dark brown, with a characteristic localization on the face in the innervation zone of the trigeminal nerve. It can be bilateral. Usually, the conjunctiva of the eye on the side of the skin lesion is involved in the process.

Nevus of Ito is distinguished by a different localization - on the skin in the supraclavicular and scapular region.

Pathomorphology. The histological picture of nevi of Ota and Ito is similar to that of blue nevus.

Histogenesis. Due to the fact that many nerve fibers are revealed among the cells of the blue nevus by the silver nitrate impregnation method, some authors believe that this tumor is of neural origin. Electron microscopy revealed melanosomes both in the cells of the simple blue nevus and in the cells of the cellular blue nevus, but they are absent from neurolemmocytes.

Plexiform spindle cell nevus (syn. deeply penetrating nevus) usually develops at a young age, the preferred localization is the scalp, cheeks, shoulder girdle area. It is a symmetrical hyperpigmented papule or nodular element not exceeding 1 cm in diameter.

Pathomorphology. Plexiform spindle cell nevus has histological features that make it similar to combined nevus, cellular blue nevus and Spitz nevus. It is also characterized by large sizes and growth into the deep layers of the dermis and subcutaneous tissue. It is a clearly defined formation in the form of a triangle with a base facing the epidermis. As a rule, single nests of nevoid melanocytosis are found in the epidermis. Distinctive features of the nevus are the presence in the dermis of narrow bundles and strands consisting of large pigmented (finely dispersed melanin) spindle-shaped and epithelioid cells interspersed with a large number of melanophages. Smaller cells resembling a common melanocytic nevus are often found. Melacites with long processes and cells with light cytoplasm, as in blue nevi, are absent. Clusters of nevomelanocytes are found around the skin appendages. There may be significant nuclear polymorphism of variable size and shape, with hyperchromasia and pseudoinclusions. Mitoses are not characteristic. A minor lymphocytic reaction is possible. Neurotropism, as in cellular blue nevi and Spitz nevi, is not a sign of malignancy.

In immunomorphological studies, nesyca cells stain positively for S-100 and HMB-45 antigens.

[ 1 ], [ 2 ], [ 3 ], [ 4 ]