Distinct tumor types in MYC10 and MYC10hommice. (A) High-power view of a MYC10 thymic macrophage tumor, comprising large cells with bulky, variably vacuolated cytoplasm and a vesicular, sometimes pleomorphic nucleus, characteristics of histiocytic sarcoma. H&E-stained section; scale bar equals 20 μm. (B) Flow cytometric analysis of typical MYC10 macrophage (Mac1⁺ F4/80⁺ Gr1^– CD19^– Thy1^–) tumor. The percentage of cells in each quadrant is indicated. (C) High-power view of a thymic MYC10^hom pre–T-cell lymphoma with lymphoblastic morphology, comprising smaller cells with indistinct cell borders. (D) Flow cytometric analysis of typical MYC10^hom pre–T-cell (Thy1⁺ TCRβ⁺ CD4⁺ CD8⁺ CD19^–) lymphoma.