Koebner's phenomenon and necrobiosis lipoidica diabeticorum.

In 1877, Dr Heinrich Koebner inflicted an experimental trauma on the uninvolved skin of a psoriatic patient. This resulted in the appearance of a typical psoriatic lesion at the site of trauma. This reaction, known as Koebner's phenomenon (KP), has subsequently been associated with several skin diseases. However, it has not been associated previously with necrobiosis lipoidica diabeticorum (NBL), a rare skin manifestation of diabetes mellitus. This report presents the unusual finding of NBL associated with KP in a patient with diabetes mellitus.