Haematopathology

Erdheim-Chester disease

• IHC: CD4, CD68, CD163

Follicular dendritic cell sarcoma

Histiocytic sarcoma

• IHC: CD4, CD45, CD68, CD163

• DNA-seq: KRAS exon 2 mutation; c.38G>A (p.Gly13Asp)

Langerhans cell histiocytosis

• IHC: CD1a

Langerhans cell histiocytosis

• IHC: langerin

Langerhans cell histiocytosis

• IHC: S100, CD1a, langerin, BRAF V600E

Langerhans cell histiocytosis

• IHC: S100, CD1a, langerin

Plasma cell myeloma

• IHC: CD138, MUM1, kappa, lambda

Rosai-Dorfman disease

• IHC: CD68, S100

Rosai-Dorfman disease

• IHC: CD68, S100