Histopathology of tumors in Fancc and Trp53 intercrossed mice. (A-F) Myeloid malignancy (histiocytic sarcoma) in a Fancc^-/-Trp53^+/- mouse. (A-B) Malignant histiocytes are observed in the red pulp of the spleen, indicated in panel A by the arrow. (C) Immunohistochemical characterization demonstrates that the malignant cells within the spleen are Mac-2⁺. (D-E) Malignant histiocytes are also observed in the liver as indicated by the arrow. (F) The malignant cells are shown to be Mac-2⁺ by immunohistochemical staining. (G-H) Dermal spindle cell tumor from the neck of a Fancc^-/-Trp53^+/- mouse shows a high mitotic index and undifferentiated cells with cigar-shaped nuclei. (I) Ovarian tumor from a Fancc^-/-Trp53^+/- mouse showing nests of round, tumor cells with rounded, pale nuclei. (J-K) Medulloblastoma of the cerebellum from a Fancc^-/-Trp53^-/- animal. Characteristic neoplastic cells with carrot-shaped nuclei, hyperchromatic coarse chromatin, and almost nonvisible cytoplasm, with frequent mitotic figures (indicated by arrows) are arranged in sheets with pseudo-rosette formations visible. (L) Adenocarcinoma of the prostate of a Fancc^-/-Trp53^-/- mouse shows malignant cells arranged in irregularly shaped glandular structures invading surrounding smooth muscle. Original magnifications: × 100 (G); × 200 (A,D,H,J); × 400 (B-C,E-F,I,K-L); and × 600 (H inset).