TABLE 1.

Clues to an acquired or congenital nature of Spitz and Reed nevi.

Reed nevus		Spitz nevus
Arguments pro congenital origin	Arguments pro acquired origin	Arguments pro congenital origin	Arguments pro acquired origin
Clinical Congenital onset possible, albeit rarely Predilection for children or young adults	Clinical Rapid growth No reports on agminated growth No reports on being constituent of a combined nevus No reports on occurrence at non-UV-exposed anatomical sites	Clinical Congenital onset possible Predilection for children or young adults Agminated pattern possible Occasional constituent of combined nevi Large size up to more than 2 cm possible Occurrence at non-UV-exposed anatomical sites	Clinical Rapid growth No reports on associated terminal hair growth
Dermatoscopy Initial globular pattern	Dermatoscopy Starburst pattern later tapering off into a reticular pattern like Clark nevus	Dermatoscopy Globular pattern as seen in other congenital nevi
Dermatopathology Largish nests Fusiform melanocytes Epitheloid or multinuclear melanocytes possible Infundibular hyperplasia Infiltration of eccrine ducts Central pagetoid spread of melanocytes possible	Dermatopathology Silhouette reminiscent of Clark nevus Horizontal growth pattern restricted to epidermis and papillary dermis, i.e., no consistent reports on dermal variants involving the reticular dermis Relatively small melanocytes No reports on associated terminal hair growth Some features in common with melanoma	Dermatopathology Silhouette may be reminiscent of Miescher or Unna nevus Infiltrative vertical growth pattern with possible infiltration of the reticular dermis or subcutis Reports on dermal variants Largish nests Epithelioid / multinuclear melanocytes frequent Infundibular hyperplasia Infiltration of eccrine ducts Myotropism, neurotropism Fibroplasia Central pagetoid spread of melanocytes possible No reports on B-RAF mutation	Dermatopathology Some features in common with melanoma