E2036. Rosai-Dorfman Disease in Breast Imaging
  1. Joshua Greenstein; University of Chicago Medicine
  2. Kirti Kulkarni; University of Chicago Medicine
Rosai-Dorfman Disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare non–Langerhans cell reactive histiocytic disorder. While RDD most commonly presents in young adults with lymphadenopathy in the head/neck region, it can also occur outside the lymph nodes as an extra-nodal variant. RDD can involve the axillary lymph nodes or the breast in its extra-nodal form; therefore, radiologists who practice breast imaging may encounter it in practice. For example, after a biopsy showing RDD the breast imager may have to decide radiology-pathology concordance and help provide further patient recommendations. Therefore, awareness of this entity and its imaging findings is helpful for those who perform breast imaging.

Educational Goals / Teaching Points
After reviewing this educational exhibit, the viewer will be able to: • Understand what Rosai-Dorman Disease (RDD) is, including its pathophysiology, common and uncommon clinical presentations, and how the extra-nodal variant can involve the breast and axilla. • Identify the radiologic features of Rosai-Dorfman Disease, which may be encountered by breast imagers.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
RDD is characterized by the recruitment of marrow monocytes from the peripheral blood into lymph node sinuses or extra-nodal sites with subsequent transformation into the immunophenotypically distinct RDD histiocytes. • The cause of RDD is unknown; autoimmune diseases and viruses such as HHV6 or Epstein-Barr virus have been suggested as potential sources. • The classic form of the disease typically presents in young adults with lymphadenopathy in the neck with slight male predominance and a mean age of 20 years. • Extra-nodal RDD has a higher tendency for a chronic relapsing course and typically affects older individuals. Steroids may play a role in treatment. • Imaging findings in the breast are typically classified as suspicious for malignancy (BIRADS-4) or highly suspicious for malignancy (BIRADS-5), and breast involvement less commonly mimics benign fibrocystic disease or a fibroadenoma. • Mammography may show a high-density, lobulated mass with a partially circumscribed or ill-defined margin. • On breast ultrasound, the mass may appear hypoechoic with indistinct or angulated margins and show increased vascularity on color Doppler imaging. Echogenic septations can also be seen in a circumscribed wider-than tall mass, which mimics a fibroadenoma. • RDD on breast MRI has been less well-described. • We will present several cases of screening-detected and palpation-detected RDD in the breast and the axillary lymph nodes. We will review the imaging and pathology findings that may be seen in RDD.

RDD is an uncommon condition that may be encountered by breast imagers either in the breast or axilla. Awareness of RDD may be particularly useful to breast imagers who may have to navigate this entity when discussing biopsy results with patients, deciding radiology-pathology concordance, and potentially rendering further recommendations.