PMC3643374_01
(a) Cellular smear showing loose clusters of cells with preponderance of histiocytes with few of them showing kidney shaped nucleus (arrow), alongwith neutrophils (N), lymphocytes (L) in the background. (Pap, x400); (b) Cells showing pseudoinclusion (arrow) (Pap, x400); (c) Binucleated histiocyte (arrow) (Giemsa, x400)
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F1
These histiocytes were binucleate, multinucleate with abundant dense cytoplasm and eccentric vesicular nuclei [Figure 1a-c]. The nuclei showed characteristic intranuclear pseudoinclusions, prominent nuclear indentations and grooves (with a kidney or coffee bean appearance) [Figure 1b]. The background showed lymphocytes, neutrophils and few eosinophils [Figure 1a].
(a) Biopsy showing variable histiocytes with mononucleate, binucleate and multinucleate cells amidst lymphocytes and polymorphs (H and E, x400); (b) Immunostaining with S100 showed diffuse positivity in the atypical histicytes (IHC, x100)
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F2
There was no necrosis, and no mitosis [Figure 2a]. On immunohistochemical staining, S-100 and CD1a were diffusely positive in all the atypical histiocytes [Figure 2b].