PMC9162837_01
(H&E x 400)- shows effacement of nodal architecture by diffuse sheets of histiocytes with abundant eosinophilic cytoplasm (a) and surrounding lympho-plasmacytic infiltrate (b). Areas where the histiocytes engulf intact chronic inflammatory cells are referred to as emperipolesis (black arrows) (c).
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fig1
Routine haematoxylin and eosin-stained sections of the lymph node biopsy showed effacement of the nodal architecture by diffuse histiocytes with surrounding lympho-plasmacytic infiltrate in areas the histiocytes engulf intact lymphocytes suggestive of emperipolesis (Figure 1).
(x100-C&D and x400-A&B) - shows diffuse cytoplasmic staining of histiocytes for S100 (2C&2D) with negative staining for engulfed inflammatory cells- emperipolesis (2A&2B).
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fig2
Immunohistochemical staining for S100 was done to rule out Langerhans cell histiocytosis and confirm a diagnosis of Rosai-Dorfman disease (presence of emperipolesis), and the section showed diffuse reactivity of the histiocytes for S100 with negative staining of the lympho-plasmacytic infiltrate (Figure 2).