Gross pathology of Eμ-TEL/PDGFβR lymphoblastic lymphoma in the I line and microscopic histopathology of tumors and affected tissues from Eμ-TEL/PDGFβR mice. (A) Gross dissection of an affected I-line mouse shows enlargement of the liver (L), spleen (S), and thymus (T), as well as massive lymphadenopathy in the cervical (C), axillary (A), and femoral (F) node groups. (B) Touch preparation of the lymph node from an affected I-line mouse shows tumor composed of intermediate-sized lymphoid cells with scant cytoplasm, finely dispersed nuclear chromatin, and a brisk mitotic rate, features of lymphoblastic lymphoma. (C) Clusters of lymphoma cells present in hepatic sinusoids. (D) Lymphoma cells in N-line mouse with T-cell mediastinal lymphoma phenotype show involvement of the lung in peribronchial distribution. (E) Lymphoma cells from the same mouse as in D infiltrating the spleen, with some residual megakaryocytes and erythroid cells. (F) Bone marrow replacement by lymphoblasts in an N-line mouse with ALL phenotype. (G) Same N-line mouse as in F showing splenic involvement with lymphoblastic leukemia (H&E).