Emperipolesis, consisting of histiocytes engulfed in well-preserved lymphocytes, was observed in the permanent paraffin-embedded tissues [patient 4, [Figure 5].
In addition to large histiocytoid or ganglion-like cells with inclusion-like nucleoli, there are spindle cells with fibrillary cytoplasm (Figure 7), large epithelioid cells with abundant eosinophilic cytoplasm (Figure 8), degenerated cells with smudged chromatin (Figure 9), neoplastic cells filled with mucoid vacuoles, so-called pseudolipoblasts found within myxoid areas (Figure 10), and large histiocytoid cells with
emperipolesis, usually containing intracytoplasmic neutrophils (Figure 11).
The presence of
emperipolesis, or the engulfment of lymphocytes and erythrocytes by histiocytes that express S-100, is considered diagnostic of RDD.
The mild and focal positivity of S100 in histiocytes and the absence of
emperipolesis in those histiocytes expressing S100 protein rule out the diagnosis of RDD.
Definitive diagnosis of RDD is based on histological assessment, whose cornerstones are identification of
emperipolesis and appropriate immunohistochemical analysis.
FNAC showed histocytic proliferative lesion with significant
emperipolesis.
A characteristic finding was the presence of lymphocytes engulfed within the histiocytic cytoplasm a feature called
emperipolesis.
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.
The diagnosis was made by histolo-gical examination showing in the left eye proliferated histiocytosis and infiltration of plasma cells and lymphocytes in a special pattern of
emperipolesis doing the diagnosis of RDD (figure 2), and in the right eye a similar pattern with foamy histiocytes but without
emperipolesis such as JXG.
Auer rods and blast forms are absent, and platelet phagocytosis and
emperipolesis may be apparent.
