Rosai-Dorfman Disease : Emperipolesis
The histiocytes in Rosai-Dorfman disease (RDD) show non-destructive phagocytosis of lymphocytes and plasma cells within their cytoplasm - a phenomenon known as emperipolesis. Several such histiocytes are seen within the lymph node sinus in this image. The lymphocytes and plasma cells are contained in intracytoplasmic vacuoles and thus protected from destruction by the hydrolytic enzymes of the histiocytes. Emperipolesis is a histologic hallmark; however, it is not specific for RDD and may be seen in other conditions. Erythrophagocytosis may also be present.