Linear lesions on the arm of a child: a diagnostic challenge.

There are a number of conditions that follow the lines of Blaschko. Linear discoid lupus erythematosus is a rare variant of chronic lupus erythematosus with less than 20 cases reported in children. It can be misdiagnosed as lichen striatus or linear morphea. We describe a 15-year-old boy with a confirmed histologic diagnosis of linear chronic discoid lupus erythematosus following the lines of Blaschko, with no signs of systemic involvement.