Extranodal Rosai-Dorfman Disease : Breast
Extranodal Rosai-Dorfman disease (ERDD) makes up between 25% to 40% of all cases of Rosai-Dorfman disease. Breast is rarely involved. More common locations for ERDD include skin, central nervous system, orbit, bones, gastrointestinal tract, and respiratory tract. However, it has been reported in virtually every major organ/site. This image shows diffuse sheets of histiocytes and small aggregates of lymphocytes infiltrating breast parenchyma. The patient was a middle-aged female who presented with progressively enlarging breast mass and axillary lymphadenopathy. The lesion was initially thought to be a lymphoma on a core needle biopsy specimen. The final diagnosis of ERDD was made on an excisional biopsy specimen.