Age distribution for the various types of hematologic malignancies, carcinomas, and sarcomas seen in irradiated Blm^+/+, Blm^m3/+, and Blm^m3/m3 mice. Each data point represents the age at necropsy in the mouse with the lesion specified. The number of cases represents the total number of cases of each lesion identified at necropsy in irradiated Blm^+/+, Blm^m3/+, and Blm^m3/m3 mice in the tumor watched up to 520 days. The vertical oval represents the mean age of tumor incidence.

Histologic features of non-lymphoid hematologic lesions in irradiated Blm^+/+, Blm^m3/+, and Blm^m3/m3 mice (all H&E, 400× original magnification). (a) Red pulp hyperplasia, a common finding in the spleen of irradiated Blm^m3/m3 mice. There is evidence of tri-lineage proliferation, namely small islands of densely hyperchromatic erythroblasts, surrounded by larger myeloblasts, immature myelocytes, ring forms, and granulocytes, plus occasional large megakaryocytes (bottom right). Red pulp sinusoids are patent and contain mature red blood cells. (b) Erythroid and myeloid hyperplasia. Red pulp sinusoids are collapsed, and cords are filled with sheets of erythroid precursors. There is additional myeloid hyperplasia. No megakaryocytes are visible in this field. (c) Acute myeloid leukemia, well differentiated, myelomonocytic. There is an excess of immature myeloblasts, with some differentiation, infiltrating and expanding the portal tracts and sinusoids of the liver. The destruction of surrounding hepatocytes also differentiates this from benign extramedullary hematopoiesis in the liver. (d) Acute myeloid leukemia, well differentiated, predominantly granulocytic. The infiltrate contains many ring forms as well as immature myeloblasts and destroys the underlying structure of the renal cortex. (e) Acute myeloid leukemia, well differentiated, predominantly monocytic. The infiltrate contains many large cells with reniform nuclei of monocytic lineage. (f) Acute myeloid leukemia, undifferentiated, infiltrating the red pulp cords and sinusoids of the spleen. At least 90% of the non-lymphoid, non-erythroid cells are immature blasts. (g) Pure histiocytic sarcoma infiltrating the liver sinusoids. The infiltrate is relatively monomorphic and is composed of well-differentiated histiocytes. (h) Histiocytic sarcoma associated with myeloproliferation. Malignant histiocytic infiltration is seen in the top left of the field, adjacent to myeloid proliferation in the red pulp. All scale bars represent 20 μm.

Histologic features of lymphomas identified in irradiated Blm^+/+, Blm^m3/+, and Blm^m3/m3 mice (all H&E, 400× original magnification). (a) T lymphoblastic lymphoma (TLL) composed of medium-sized lymphoid blasts with inconspicuous nucleoli. Mitotic activity is high, resulting in a starry sky appearance. (b) B lymphoblastic lymphoma (BLL) composed of medium-sized lymphoid blasts with inconspicuous nucleoli. Some BLL lacked the starry sky appearance. (c) Follicular B cell lymphoma (FBL) composed of a mixed population of small, cleaved centrocytes and larger centroblasts with multiple prominent peripheral nucleoli. Less than 50% of the tumor cell population is centroblasts. (d) Diffuse large B cell lymphoma, immunoblastic (IBL). More than 50% of the cells are immunoblasts/centroblasts. Note the prominent large bar-shaped eosinophilic nucleoli within the large immunoblasts. Often this lymphoma was also associated with a starry sky appearance due to the high mitotic activity of the immunoblasts. (e) Small B cell lymphoma (SBL). This low-grade lymphoma is composed of small B lymphocytes similar to the small lymphocytes in the human counterpart lymphoma, CLL. (f) Plasmacytoma/plasmacytoid lymphoma, composed of small- to medium-sized cells with plasmacytoid nuclei and abundant cytoplasm. All scale bars represent 20 μm.