Erdheim-chester disease presenting as bilateral clinically malignant breast masses.

Erdheim-Chester disease is a rare non-Langerhans cell histiocytosis of unknown etiology, the commonest sites of involvement being the long bones, skin, orbit, pituitary and retroperitoneum. Breast involvement is rare, with only four reported cases in the English literature. We present a case of a 78-year-old female presenting with bilateral clinically malignant breast masses, with mammographic and ultrasound findings suggestive of locally advanced bilateral breast cancer.