Figure 5

A, B, C, D, E and F. Recurrent tibial tumor (2009): area with classic histology of benign giant cell tumor of bone. The nuclei of the two components are similar, with smooth contours and relatively condensed chromatin (A original magnification ×290). Immunostain for CD4 (B original magnification ×290) and CD43 (B, inset; the smaller, darker CD43+ cells are T cells original magnification ×290). Area with frank malignant transformation characterized by large and pleomorphic cells with vesicular and irregularly shaped nuclei, prominent nucleoli and frequent mitotic figures (C). Immunostain for P63 (D, original magnification ×290). Immunostain for MIB-1 in benign (E) and malignant (F) areas (original magnification × 145).