Disease

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© Springer Nature Switzerland AG 2021

R. Reti, D. Findlay (eds.)Oral Board Review for Oral and Maxillofacial Surgerydoi.org/10.1007/978-3-030-48880-2_16

16. Hematologic Disease

Jaclyn A. Tomsic1   and Aaron D. Figueroa2
(1)

University Hospitals, Department of Surgery, Cleveland, OH, USA
(2)

University of Iowa Hospitals and Clinics, Hospital Dentistry Institute, Oral and Maxillofacial Surgery, Iowa City, IA, USA
 
 
Jaclyn A. Tomsic
Keywords

AnemiaLeukemiaHemophiliaVon Willebrand’s diseaseLymphomaThalassemiaSickle cell anemiaHereditary spherocytosisMean corpuscular volume (MCV)Factor V LeidenCryoprecipitateFresh frozen plasma

Anemia

  • Anemia is defined as a decrease in red blood cells (RBC), leading to less oxygen carrying capacity and delivery to end organs.

  • Normal hemoglobin in adult males is 14–18 g/dL and in adult females 12–16 g/dL.

  • Normal Hct in adult males is 40–52% and in adult females is 35–47%.

  • Anemia may be caused by disorders of bone marrow production, red cell maturation, increased destruction, and iron deficiency. Anemia is subclassified into microcytic, normocytic, and macrocytic (Table 16.1). Clinical symptoms of anemia are fatigue and decreased exercise tolerance.

Table 16.1

Type of types of anemia and examples [1]

Microcytic

Normocytic

Macrocytic

Iron deficiency

Thalassemia

Sideroblastic anemia

Lead poisoning

Acute blood loss

Hemolysis

Anemia of chronic disease

Anemia of renal failure

Myelodysplastic syndromes

Aplastic anemia

Hemolytic anemias

Folate deficiency

Vitamin B12 deficiency

Drug toxicity

Alcoholism/chronic liver disease

Iron and lab studies are used to determine the type and etiology of anemia. The most common studies used are as follows:

  • Ferritin: marker of iron stores (also an acute phase reactant).

  • TIBC (total iron binding capacity): indirect measure of transferrin saturation levels.

  • Transferrin: protein which transports iron within the blood.

  • MCV (mean corpuscular volume): average RBC volume; this value categorizes anemia:

    • Microcytic: MCV ≤ 80 fL

    • Normocytic: MCV = 80–100 fL

    • Macrocytic: MCV ≥ 100 fL

  • Reticulocyte: immature erythrocyte (new RBC that is usually 1–1.5 days old).

  • Reticulocyte count: fraction of RBCs consisting of reticulocytes that indirectly indicates the bone marrow activity of the erythrocyte line; expressed as a percentage; normal value 1%.

Microcytic Anemias

Iron Deficiency Anemia

  • Etiology is the decreased synthesis of heme. Iron deficiency anemia is the most common cause of anemia in the United States of all ages and both genders.

  • Causes of iron deficiency anemia:

    • Blood loss (most common) – PUD, gastritis/NSAIDs, polyps/colorectal cancer, menorrhagia.

    • Increased utilization – pregnancy, infants/children.

    • Decreased intake – infants/children, elderly.

    • Decreased absorption – celiac sprue.

Treatment
  • Iron supplementation

  • Transfusion in specific cases for severe anemia

  • Treat the underlying disease process

Thalassemia Anemias

A group of autosomal recessive anemic disorders due to the abnormal production of globin chains.

Alpha-thalassemia
  • Decrease in synthesis of the alpha-globin chain of hemoglobin (Hgb).

  • Common in Southeast Asia and Black Americans.

  • Four genes control the production of the alpha chain of Hgb; combinations of deletions of 1, 2, 3, or all 4 of these chains cause different types and degrees of alpha-thalassemia.

  • One or two deletions cause mild anemia with little symptoms and no need for treatment.

  • Three gene deletions lead to HbH or four beta-chain disease, which causes a severe hemolytic anemia due to macrophage destruction of RBCs due to the excess beta chains.

  • Four gene deletions are called Hb Bart and is incompatible with life.

Beta-thalassemia
  • Decrease in the synthesis of the beta-globin chain of Hgb.

  • Common in Black Americans, Greeks, and Italians.

  • There are mild and severe forms:

    • Beta-thalassemia minor: mild microcytic anemia due to DNA splicing defect; decrease in HbA, increase in RBC count, HBA2, and ferritin production; no treatment.

    • Beta-thalassemia major: severe hemolytic anemia due to a nonsense mutation with formation of a stop codon; no production of HbA, increased production of HbA2 and HbF; these patients have lifelong danger of iron overload and therefore lifelong need for transfusion.

Macrocytic Anemia

  • Increase in RBC size, commonly caused by either Vitamin B12 or folate deficiency.

  • Most common cause of Vitamin B12 deficiency is pernicious anemia (decrease in intrinsic factor due to autoimmune destruction of gastric parietal cells).

  • Most common cause of folate deficiency is alcoholism.

  • Vitamin B12 is found in meat, eggs, and dairy products.

  • Folate is found in green vegetables and animal proteins.

  • Characteristic difference between Vitamin B12 and folate deficiency: neurologic disease (seen in Vit B12 deficiency but not folate deficiency).

  • Lab findings in both: decreased Vitamin B12 or folate, increased homocysteine, pancytopenia and hypersegmented PMNs (PMN with more than five lobes).

  • Other less common causes of macrocytic anemia: chemotherapy, hemolysis, liver disease, myelodysplastic syndromes, hypothyroidism

Normocytic Anemia

There are a number of conditions under this category that are beyond the scope of this, text but the following will be touched upon briefly.

Anemia of Chronic Disease (ACD)

  • Most common anemia in hospitalized patients.

  • Common causes: chronic inflammation (rheumatoid arthritis, tuberculosis), alcoholism, malignancy.

  • Caused by decreased synthesis of heme.

  • Lab findings: decreased iron, TIBC and iron saturation; increased ferritin

  • ACD is microcytic 10–30% of the time.

Acute Blood Loss or Hemorrhage

  • This may occur due to external causes (trauma, peptic ulcers) or internal causes (ruptured abdominal aortic aneurysm) and results in signs of volume depletion such as hypotension and tachycardia.

Aplastic Anemia

  • Aplastic anemia is a bone marrow disorder.

  • There are many causes of aplastic anemia and morbidity is high as only 10% of cases make a full recovery.

  • In general, there is a destruction of multipotent myeloid stem cells with inadequate production of differentiated cell lines.

  • The majority of cases are idiopathic; the most common known causes are drugs, commonly chemotherapy drugs (alkylating agents, antimetabolites).

  • Other causes include chemical toxins (insecticides, benzene, parathion), viral infection (EBV, CMV, parvovirus B19, non-A and non-B hepatitis), and whole body radiation therapy.

  • Lab findings: pancytopenia, low reticulocyte count (hallmark), hypocellular bone marrow.

  • Clinical findings: fatigue, malaise, pallor, mucosal bleeding, petechia, infection.

  • Treatment: withdrawal of offending agent, RBC and platelet transfusion, bone marrow transplant.

Hemolytic Anemias [2]

In general, hemolytic anemias are characterized by hemolysis of erythrocytes. These processes exhibit an increase in serum bilirubin leading to jaundice and an increase in reticulocytes as the bone marrow compensates for the loss of red blood cells.

Autoimmune Hemolytic Anemia (AIHA)

  • Extravascular hemolysis due to the excessive destruction of RBCs by the liver and the spleen by autoantibodies against foreign RBC antigens.

  • Warm type (70%) associated with IgG antibodies.

  • Cold type (30%) associated with IgM antibodies.

  • SLE (systemic lupus erythematosus) is the most common cause of AIHA.

  • The direct antihuman globulin test (DAT or Coombs test) is the most important marker for AIHA.

Hereditary Spherocytosis

  • An autosomal dominant RBC membrane defect.

  • Intrinsic membrane defect of ankyrin or spectrin that causes extravascular hemolysis due to loss of RBC membrane and formation of spherocytes (small, round RBCs with no central pallor).

  • Lab findings: increase in MCHC, RDW, RBC osmotic fragility (diagnostic for hereditary spherocytosis); normocytic anemia with spherocytes.

  • Clinical findings: jaundice (due to increased unconjugated bilirubin), increased incidence of gallstones (due to increased conjugated bilirubin), splenomegaly.

  • Treatment: splenectomy (Howell-Jolly bodies present after splenectomy).

Sickle Cell Anemia (SCA)

  • Autosomal recessive disorder – intrinsic defect causing a hemoglobinopathy that causes extravascular hemolysis of sickled RBCs.

  • Most common hemoglobinopathy in patients of African descent.

  • SCA is a missense point mutation where valine is substituted for glutamic acid at the sixth position of the beta-globin chain of Hb; this mutation causes sickling of RBCs.

  • Key pathologic processes in SCA: severe hemolytic anemia and vaso-occlusive crises (Table 16.2). Management is based on symptoms. Fluid hydration, pain management (PO or IV), oxygen therapy (O2 < 92%), and steroids.

  • Treatment: hydroxyurea (increases HbF which prevents sickling) and bone marrow transplant.

Table 16.2

Clinical findings and complications of sickle cell anemia

Clinical findings and complications in SCA (HbSS)

Aplastic crisis (due to parvovirus B19 infection)

Dactylitis (swelling of hands and feet in infants)

Acute chest syndrome (vaso-occlusion of pulmonary capillaries; high morbidity)

Aseptic necrosis of femoral head

Autosplenectomy (due to accumulation of sickled cells)

Increased risk of infection from encapsulated organisms (Streptococcus pneumonia, Neisseria meningitidis, Haemophilus influenzae type b) and Salmonella paratyphi osteomyelitis

Pain crises (due to vaso-occlusion), e.g., priapism

Splenic sequestration crisis

Leukemia

  • Leukemia is a disease of the mesenchymal cells of the blood in which there is an abnormal proliferation or an increased lifespan of myeloid or lymphoid cells.

  • In the simplest form, all blood cells originate from a pluripotent stem cell, which can then differentiate into a myeloid (bone marrow) precursor or lymphoid (lymphatic tissue) precursor. Therefore, leukemias are classified as either myeloid or lymphoid and then subclassified as acute or chronic depending on its characteristics.

  • Myeloid cells form – erythrocytes, polymorphonuclear lymphocytes (PMNs), macrophages/monocytes, platelets, eosinophils, and basophils.

  • Lymphoid cells form – plasma cells (B cells), T cells, or natural killer (NK) cells.

  • Pathogenesis of leukemias – block in stem cell differentiation leading to proliferation of neoplastic leukemic cells.

  • General characteristics of all leukemias:

    • Increased number of circulating leukocytes in the blood.

    • Infiltration of the bone marrow by leukemic cells (both mature and immature);

    • Most common sites of leukemic infiltration are the spleen, liver, lungs, skin, lymph nodes.

    • Bone marrow failure: anemia (decreased RBCs), granulocytopenia of mature WBCs (leading to infections), and thrombocytopenia (decreased platelets) leading to hemorrhage.

Myeloid Leukemias [3, 4, 5]

  • In myeloid leukemias, there is a somatic gene mutation resulting in the loss of control at one level of production which then leads to increased, decreased, or normal production of the cells of that line.

  • The production of the other cells in that cell line is then indirectly disturbed. This disturbance, which can be quantitative or qualitative, causes crowding or suppression within the bone marrow.

  • Therefore a common characteristic of myeloid leukemias is their infiltration of the bone marrow with a decreased number of normal myeloid cells of poor function.

Acute Myelogenous Leukemia (AML) [6, 3]
  • This type of leukemia produces an increase in the number of immature myeloid cells (20%) in the bone marrow leading to bone marrow failure.

  • Hematopoietic insufficiencies in the form of granulocytopenia, thrombocytopenia, and anemia are found.

  • The incidence of AML is 2.3/100,000 people and increases with age and most commonly occurs between the ages of 15 and 59.

  • AML accounts for upwards of 80% of acute leukemia in adults. It is more common in men than women. Common risk factors for AML are listed in Table 16.3.

  • Fatigue is the most common presenting symptom. Other symptoms include dyspnea on exertion, dizziness and in the older patient angina, weight loss, anorexia, fever, and infection susceptibility.

  • Gingivitis/swollen gums (leukemic infiltration) are symptoms of the neutropenia common in AML.

  • Coagulation irregularities (bleeding and easy bruising) caused by thrombocytopenia.

  • Physical examination yields splenomegaly (due to infiltration with leukemic cells), fever, infection and lymphadenopathy, and evidence of coagulopathy (ecchymosis, telangiectasia, petechiae, purpura, and bleeding gums).

  • Work up includes blood tests (CBC, coagulation studies, blood smear, BMP, blood culture), bone marrow aspiration, and appropriate imaging.

  • CBC – reveals anemia and thrombocytopenia; patients with AML may have high, normal, or low WBC counts.

  • Coagulation studies – AML patients most commonly develop DIC (disseminated intravascular coagulation).

  • Blood smear – increased number of circulating myeloblasts and Auer rods (splinter or rod-shaped granules within the cytosol of leukemic myeloblasts, most often found in the AML M3 subtype). Schistocytes or “helmet cells” (fragmented irregularly shaped RBCs with pointed ends common in DIC).

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Jul 23, 2021 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Disease
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