Abstract
Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis of unknown aetiology. The most common sites of involvement are the long bones, skin, orbit, pituitary and retroperitoneal space. Isolated breast involvement is rare in the literature. ECD of the breast has been rarely reported. ECD should be considered in the differential diagnosis of histiocytoid breast lesions, including fat necrosis and histiocytoid invasive mammary carcinoma. In this case report, we present an unusual presentation isolated breast involvement of ECD with radiological and histopathology findings.