Spitz nevus: causes, symptoms, diagnosis, treatment

Spitz nevus (syn.: spindle cell and/or elyteloid cell nevus, juvenile melanoma) is an unusual nevoid melanocytic neoplasm that has clinical and morphological similarities with malignant melanoma of the skin. The question of inheritance has not been resolved. It can be congenital. It occurs with a frequency independent of gender. There are reports of familial cases.

It develops mainly in children. Clinically, a nevus is usually an asymptomatic tumor-like formation, hemispherical or flat, with clear boundaries. The size is usually small, less than 1 cm, the color varies from light red to dark brown and even black. The consistency of the nevus is soft-elastic or dense. The surface is smooth, devoid of hair, less often hyperkeratotic, warty. In rare cases, bleeding and ulceration are possible. At first, the tumor grows quickly, and then can remain in a stationary state for many years. There are cases with multiple, usually grouped nevi - from 20 to 50 elements. The localization of the nevus, according to research, depends on its clinical and morphological type. Thus, flat hyperpigmented variants are more often localized on the extremities, and non-pigmented red formations are usually found on the face and scalp.

Pathomorphology. Histologically, a nevus may be borderline, mixed, or intradermal. The most common is the sour cream variant. In most cases, both spindle-shaped and epithelioid cells are determined, but a nevus may consist of either only epithelioid cells or only spindle-shaped cells. The pigment content in nevomelanocytes is variable. Atypism and polymorphism of cellular elements are often expressed; pseudoinclusions (cytoplasmic invagination) are detected in the nuclei of some cells.

Characteristic features of a nevus are: symmetry of the nevus structure (in the horizontal plane): clear lateral borders with a predominance of nests along the periphery of the nevus, rather than isolated melanocytosis; nests of melanocytes in the epidermis tend to merge with each other, surrounded by cracks-artifacts; a decrease in the size of cells in the underlying parts of the dermis compared to the overlying ones: the presence of eosinophilic Camino bodies in the epidermis or upper dermis; edema and telangiectasia in the upper dermis. Possible weakly discharged migration of melanocytes into the suprabasal layers of the epidermis. Mitoses are only superficial, usually no more than one in the field of view at high magnification.

A special variant is the pigmented spindle cell nevus of Reed. As a rule, it is located superficially - in the epidermis and papillary layer of the dermis, is characterized by the presence of exclusively spindle-shaped cells, a significant pigment content, and is often accompanied by atypia of cellular elements.

During immunomorphological examination, nevus cells stain positively for vimentin and S-100 antigen, and variably for HMB-45.