Erdheim-Chester disease: a histiocytic disorder more than skin deep.

Erdheim-Chester disease is a rare potentially malignant systemic non-Langerhans cell histiocytosis. Although classically described in the pulmonary system and long bones, cutaneous involvement has been chronicled in 2 previous case reports. Herein, we describe a single systemic case afflicting an elderly man with synchronous multifocal cutaneous disease. The previous literature and pertinent differential diagnosis will be discussed.