Erythroid leukemia, megakaryocytic leukemia, histiocytic sarcoma, and mast cell sarcoma in mice.

(A) Erythroid leukemia. Note erythroblasts in liver (H&E, × 1000). (B) Megakaryocytic leukemia. Note various forms of immature neoplastic megakaryocytes (H&E, × 400). (C) (D) Histiocytic sarcoma: a relatively common tumor in mice that is rare in humans (H&E, × 400). (C) A solid sheet of eosinophilic histiocytes forming elongated or round patterns is seen. (D) Histiocytic sarcoma showing multinucleated histiocytes and vascular invasion in the liver. (E) A mast cell sarcoma showing a uniform population of small cells with prominent granular eosinophilic cytoplasm (H&E, × 400). (F) Giemsa stain of mast cell sarcoma shows strong metachromasia of many tumor cells. Metachromatic staining is also revealed by toluidine blue stain (Giemsa, × 400).