low power H&E stained section of Spitz naevus with “RD” of naevus cells
A descriptive term for the “dropping” of fascicles of uniform, pale spindled naevus cells from an irregularly hyperplastic epidermis into the reticular dermis among collagen bundles. This histopathological finding has been fancifully likened to raindrops. As the fascicles drop deeper into the dermis, the cells become smaller and more mature.
Raining down (RD) is a feature of Spitz naevus, and a soft criterion of benignancy. Other features of Spitz naevus include a widened and oedematous papillary dermis replete with ectatic blood vessels