Immunophenotype of floret-like giant cells within neurofibromatosis type 1-associated cutaneous neurofibroma. (A) Most floret-like giant cells (arrows) exhibited intense cytoplasmic staining with the generic mesenchymal intermediate filament protein vimentin, and (B) shared immunoreactivity for the myofibroblastic marker CD34 (arrows) with gracile endoneurial-type fibroblasts (arrowheads) that tend to ubiquitously occur within neurofibromas. (C) Whereas the main population of neurofibroma tumor cells is positive for S100 protein (arrowheads), floret-like giant cells (arrows) are not. Further, consistently negative reactions included (D) smooth muscular actin (arrows), as well as the perineurial markers (E) EMA (epithelial membrane antigen) (arrows), and (F) GLUT-1 (glucose transporter 1) (arrow). Original magnification: (A) through (F) ×200.