Rare presentations and literature review of Rosai Dorfman disease of the breast

Abstract Introduction Rosai-Dorfman disease (RDD) is a rare, idiopathic, proliferative disorder of histiocytes usually involving head-neck lymph nodes. It can also involve extra nodal sites like skin, nasal sinuses, and soft tissue. It rarely affects the breast. Case presentation We present three unusual case scenarios of breast RDD. One presented with breast lump, clinico-radiologically mimicking early breast cancer. The second case was thought to be de-novo metastatic breast cancer, but was found to have disseminated RDD of breast, lymph nodes and bones. The third patient was that of cervical lymphadenopathy in a breast cancer survivor masquerading as recurrence. In all 3, histopathology showing emperipolesis and immunohistochemical staining with S100 clinched the diagnosis. Discussion The diagnosis of RDD is made by histopathology. The classic histological picture consists of a lymphoid rich associated infiltrate, atypical nuclei of the histiocytes and lack of fat necrosis or acute inflammatory cells. These histiocytes typically stain positive with S100 and CD168 on immunohistochemistry. Hence, an excision biopsy is often necessary, and mostly the only treatment needed. However, if the disease is disseminated or has massive lymphadenopathy, a course of oral steroids or chemotherapy is indicated. Conclusion RDD of the breast usually has an indolent, benign, and non-aggressive course that requires minimum treatment. A high index of suspicion and accurate histopathological diagnosis is utmost important for proper management.