Histologic and immunohistochemical studies and schematic representation of somatic translocation. (A) Hematoxylin-and-eosin–stained section, original magnification ×20, showing diffuse sheets of histiocytoid cells set in a fibroinflammatory background. Immunohistochemical staining shows diffuse positivity for CD163 (B), CD33 (C), and factor XIIIa (D). No staining is noted for BRAF VE1 (E) and cyclin D1 (F) stains diffusely positive. (A-F) Scale bars, 200 μm. (G) Schematic representation of the MRC1-PDGFRB translocation.