Sean Klepper M.D.
Stephen Lyle, M.D., ...
- Peak incidence between 10 and 30 years of age
- Most common on the face, upper trunk and proximal extremities
- Presents as small, raised bluish lesion mimicking blue nevus
- Well-circumscribed, symmetric lesion within the dermis, sometimes also displaying a junctional component
- The architecture is that of a wedge-shaped proliferation of tightly packed, pigmented spindle cells
- The spindle cells show a diffuse arrangement in the upper dermis, and become arranged into discreet fascicles as they move into the deep dermis
- The spindle fascicles may have a bulbous contour in the deeper aspects of the lesion, and may extend into the subcutaneous fat.
- The nevus cells are often closely associated with neurovascular and adnexal structures in the deeper dermis.
- Melanophages are often present in association with the nevus cells.
- Focal significant cytologic atypia is often present, and occasional mitoses (1 to 2 per square millimeter) may be seen.