Sonographic features of Rosai-Dorfman disease in the breast: A case report.

Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is an uncommon histiocytic disease of the lymph nodes. Extranodal presentation, especially in breast parenchymal tissue, is rare. A 54-year-old woman presented with a painful and palpable lump in the right breast. Ultrasonography revealed an irregular, indistinct, hypoechoic mass with a hyperechoic halo. Pathological analysis revealed proliferation of large histiocytes and stromal fibrosis with emperipolesis and positive immunoreactivity for S-100 and CD68. The clinical and radiologic manifestations of Rosai-Dorfman disease may vary, and differentiation from other inflammatory diseases and malignancies is challenging; thus, accurate pathological diagnosis plays an important role in appropriate management.