Erdheim-Chester Disease of the Breast: First Review and First Case of Isolated Severe Gynecomastia.

(1) Introduction: Erdheim-Chester disease (ECD) is a life-threatening condition and often a diagnostic challenge. It has recently been classified as a hematopoietic tumour, and the cases of ECD reported in the literature has dramatically increased during the last 15 years. (2) Methods: We describe the case of a 57-year-old male patient with severe gynecomastia, with a detailed description of his diagnostic and consequent surgical operation.