Progressive idiopathic atrophoderma of Pasini and Pierini.

Atrophoderma of Pasini and Pierini was first described in 1923. Asymptomatic and usually located on the trunk, it presents as bluish patches, smooth and without atrophy, with a characteristic "cliff-drop" border. It appears to be clinically distinct and histopathically separate from morphea but easily confused with it. There is no effective treatment but its course is benign, often with spontaneous termination.