Painless B/L Lymphadenopathy, fever, leukocytosis
H&E: Marked sinus expansion by histiocytes, emperipolesis (lymphocytes, neutrophils, plasma cells in cytoplasmic vacuoles)
IHC: S100+, CD68+, CD163+, CD1a-, Langerin -
Non clonal. BRAF V600 E mutation in rare cases have been reported
Good prognosis, spontaneous regression
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