Many of these histiocytes classically exhibit emperipolesis
of lymphocytes and plasma cells.
These histiocytes were positive for S-100 protein (figure 1), CD68, HAM-56, and lysozyme, and they showed emperipolesis
Many histiocytes showed emperipolesis
, with engulfed and partially digested plasma cells, lymphocytes and neutrophils (Fig.
Thrombocytopenia and emperipolesis
in a patient with hepatitis a infection.
Auer rods and blast forms are absent, and platelet phagocytosis and emperipolesis
may be apparent.
The FNAB tests showed numerous lymphocytes and histiocytes with emperipolesis
(Figure 3, B); Ziehl-Neelsen stain results for acid-fast bacilli were negative, and the features were considered most consistent with Rosai-Dorfman disease.
The histiocytes have abundant foamy cytoplasm; some have small lymphocytes in the cytoplasm as a result of emperipolesis
The cellular process is composed of a brisk, inflammatory infiltrate containing large histiocytes that characteristically demonstrate emperipolesis
, the phagocytosis of neutrophils, lymphocytes, and plasma cells (Figure 11, B).
Extranodal disease may be more difficult to identify histopathologically, as the emperipolesis
may be obscured by extensive fibrosis.
Prominent macrophages and microglia seen in the biopsy were not associated with Langerhans histiocytes or emperipolesis
, thus excluding Langerhans histiocytosis and Rosai-Dorfman disease.
Histologically, there are sheets of large epithelioid histiocytes with prominent nucleoli, exhibiting emperipolesis
(lymphocyte, plasma cell, or neutrophil phagocytosis), admixed with prominent small lymphocytes and polytypic plasma cells (Figure 5).
Immunohistochemical studies were performed and the histiocytes were labeled by CD68 (Dako, Carpinteria, California) and were focally positive for S100 protein (Biogenex, San Ramon, California), highlighting the emperipolesis
, and were negative for CD1a (Immunotech, Brea, California), supporting the diagnosis of Rosai-Dorfman disease.