Myelophthisic anemia is caused by extensive infiltration of the marrow by tumors or other lesions. It most commonly is associated with metastatic breast, lung, or prostate cancer. Other tumors, advanced tuberculosis, lipid storage disorders, and osteosclerosis may produce a similar clinical picture. The principal manifestations include anemia and thrombocytopenia; in general, the white cell series is less affected. Characteristically misshapen red cells, some resembling teardrops, are seen in the peripheral blood. Immature granulocytic and erythrocytic precursors also may be present (leukoerythroblastosis) along with mild leukocytosis. Treatment is directed at the underlying condition.
ANEMIAOFDIMINISHEDERYTHROPOIESISunsteadiness of gait and loss of position sense, particularly in the toes. Although the anemia responds dramatically to unsteadiness of gait and loss of position sense, particularly in the toes. Although the anemia responds dramatically to •Causedbychronicbleedingorinadequateironintake;resultsininsufficienthemoglobinsynthesisandhypochromic,microcyticredcells
Anemia of Chronic Inflammation •Causedbyinflammatorycytokines,whichincreasehepcidinlevelsandtherebysequesterironinmacrophages,andalsosuppresserythropoietinproduction
Resultsinenlargedabnormalhematopoieticprecursors(megaloblasts),ineffectivehematopoiesis,macrocyticanemia,and(inmostcases)pancytopenia http://ebooksmedicine.net •Causedbybonemarrowfailure(hypocellularity)resultingfromdiversecauses,includingexposurestotoxinsandradiation,idiosyncraticreactionstodrugsandviruses,andinheriteddefectsintelomeraseandDNArepair
Polycythemia, or erythrocytosis, denotes an increase in red cells per unit volume of peripheral blood. It may be absolute (defined as an increase in total red cell mass) or relative. Relative polycythemia results from dehydration, such as occurs with water deprivation, prolonged vomiting, diarrhea, or the excessive use of diuretics. Absolute polycythemia is described as primary when the increased
Table 12.5 Pathophysiologic Classification of Polycythemia
Abnormalproliferationofmyeloidstemcells,normalorlowerythropoietinlevels(polycythemiavera);inheritedactivatingmutationsintheerythropoietinreceptor(rare)
Adaptive: Lungdisease,high-altitudeliving,cyanoticheartdisease
Paraneoplastic: Erythropoietin-secretingtumors(e.g.,renalcellcarcinoma,hepatomacellularcarcinoma,cerebellarhemangioblastoma)
Surreptitious: Enduranceathletes red cell mass results from an autonomous proliferation of erythroid progenitors, and secondary when the excessive proliferation stems from elevated levels of erythropoietin. Primary polycythemia (polycythemia vera) is a clonal myeloid neoplasm considered later in this chapter. The increases in erythropoietin that cause secondary forms of absolute polycythemia include a variety of causes (
Table 12.5
Disorders of white cells include deficiencies (leukopenias) and proliferations, which may be reactive or neoplastic. Reactive proliferation in response to a primary, often microbial, disease is common. Neoplastic disorders, although less common, are more ominous: They cause approximately 9% of all cancer deaths in adults and a staggering 40% in children younger than 15 years of age.
Presented next are brief descriptions of some nonneoplastic conditions, followed by more detailed considerations of the malignant proliferations of white cells.