, 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.