Clinical appearance of tumors in DTG mice. (A) Peripheral-blood smear from a 3-week-old DTG mouse showing leukemic atypical large blastic lymphoid cells morphologically similar to lymphomas subsequently arising in peripheral lymphoid tissues (original magnifications: left, ×400, right, ×1000). (B) Gross necropsy photo of DTG mouse, showing widespread and extensive peripheral lymphadenopathy indicative of lymphomatous involvement as histologically shown in panel D. Arrows indicate lymph nodes. (C) Bone marrow from a 3-month-old DTG mouse showing large “blastoid” lymphoma cells (original magnification, ×1000). (D) Histopathologic H&E-stained paraffin section of the spleen showing diffuse effacement of an enlarged lymph node diffusely replaced with large “blastoid” lymphoma cells with admixed large “pink” histiocytes characteristic of MCL-BV (original magnification, ×400). (E) Lymphomatous involvement in the gastrointestinal tract showing diffuse involvement of the lamina propria and submucosa (original magnification, ×400). (F) Liver involvement in DTG mice, showing perivascular infiltrates of lymphoma cells (original magnification, ×400). (G) Comparison of DTG lymphoma cell line with 2 representative MCL-BV cell lines from patients showing morphologic similarity between human MCL-BV and the DTG murine model (H&E; original magnification, ×1000).