A 60 year old male patient complains of weakness and abdominal pain. General physical examination reveals marked splenomegaly and moderate hepatomegaly. Histopathologic findings are suggestive of leukoerythroblastosis. This patient may be suffering from:

The peripheral blood smear is markedly abnormal. Red cells often exhibit bizarre shapes (poikilocytes, teardrop cells), and nucleated erythroid precursors are commonly seen along with immature white cells (myelocytes and metamyelocytes), a combination of findings referred to as leukoerythroblastosis. Abnormally large platelets often are present as well. The bone marrow in advanced cases is hypocellular and diffusely fibrotic, whereas early in the course it may be hypercellular and have only focal areas of fibrosis. Throughout the course, marrow megakaryocytes are present in clusters and have characteristic hyperchromatic nuclei with “cloudlike” outlines. Marked splenomegaly resulting from extensive extramedullary hematopoiesis, often associated with subcapsular infarcts, also is typical. The spleen may weigh as much as 4000 g, roughly twenty times its normal weight. Moderate hepatomegaly, also due to extramedullary hematopoiesis, is commonplace.