Histiocytic Sarcoma

• Malignant cells resembling histiocytes: large eccentric placed, oval nuclei with vesicular chromatin and a prominent single, irregular nucleolus; nuclei may be grooved; cytoplasm is abundant and eosinophilic, and may be foamy or vacuolated.
• Positive markers: CD68, CD163, CD14, CD4, CD11c, lysozyme, alpha 1-antitrypsin, CD45, HLA-DR
• S100 may be positive
• Negative markers: follicular dendritic markers (CD21, CD23, CD35) and langerhans cell markers (langerin, CD1a)