Sean Klepper M.D.
Stephen Lyle, M.D., ...
Also known as: spindle and epithelioid cell nevus of large spindle and/or epithelioid cells, spindle cell nevus, juvenile melanoma, benign juvenile melanoma
- Benign nevus which rarely transforms to melanoma
- Most common in children and adolescents
- May occur anywhere, but there is a predilection for the face and extremities
- Typically solitary, although grouped and disseminated forms exist
- Presents as a small red-pink or skin-colored dome-shaped nodule
- Approximately two thirds are compound.
- Cytologic Features (both features must be present in order to make the diagnosis):
- Spindle and/or epithelioid cells
- Spindle: elongated cells with central nuclei approximately the same size as those of keratinocytes, regular nuclear contours, dispersed to vesicular chromatin, usually a single central nucleolus; arranged in fascicles or elongated nests, typically in a vertical orientation or with a concentric orientation of the cells within their nest
- Epithelioid: large round, oval or polygonal cells with well-defined cell borders, nuclei similar to those of the spindle cells, abundant cytoplasm (eosinophilic to basophilic, sometimes with a ground-glass appearance, similar to the cytoplasm of the spindle cells); multinucleated cells are sometimes seen
- Monomorphism of the majority of the nevus cells (occasional pleomorphic cells may be seen)
- Architectural Features:
- Sharp lateral demarcation
- Maturation (zonation): as the lesion progresses deeper into the dermis, the nests--as well as the cells themselves--become progressively smaller, and in the deeper aspects of the lesion single cells interspersed in a noninvasive fashion between collagen bundles may be seen; in addition, if pigment is present in the lesion, it tends to be most prominent in the more superficial aspects
- Mitoses range from nonexistent to numerous. If they are present, they should be most prominent in the more superficial aspects of the nevus, with no more than rare mitoses in the deep aspect.
- Kamino bodies are often present at the dermal-epidermal junction. Although they are nonspecific, they are somewhat helpful in making the distinction from melanoma, in which they are usually absent.
- Pagetoid spread is not a typical feature of Spitz nevus, and if prominent it should alert one to the possibility that the lesion actually represents a melanoma.
- A commonly observed phenomenon is that of cleft-like space between nevus cells and between nevus nests and the epidermis at the dermal-epidermal junction, representing a form of retraction artifact.
- Spitz nevi often involve adnexal structures.
- A perivascular, or less commonly diffuse, inflammatory infiltrate is often present.
- Epidermal hyperplasia is often seen.
- Vascular dilatation and dermal edema are commonly present.