CHAPTER 19 - Bone Marrow Failure

Bone Marrow Failure

Reduction or cessation of blood cell production affecting one or more cell lines, often resulting in pancytopenia.

Pancytopenia

Decreased numbers of circulating red blood cells (RBCs), white blood cells (WBCs), and platelets seen in severe cases of bone marrow failure.

Pathophysiology of Bone Marrow Failure

Includes destruction of hematopoietic stem cells, premature senescence, ineffective hematopoiesis, disruption of the microenvironment, decreased production of growth factors, and loss of hematopoietic tissue.

Clinical Consequences of Bone Marrow Failure

Varies from asymptomatic to fatal consequences if untreated; includes symptoms like fatigue, bleeding, and increased infection risk.

Aplastic Anemia

A bone marrow failure syndrome characterized by damaged or defective stem cells, leading to pancytopenia and hypocellular marrow.

Acquired Aplastic Anemia

A form of aplastic anemia that can be idiopathic or secondary, with no known cause or associated with an identified cause.

Etiology of Aplastic Anemia

Includes drug exposure, chemicals, radiation, infections, and autoimmune mechanisms.

Incidence of Aplastic Anemia

Approximately 1 in 500,000 in North America and Europe, higher in Asia and East Asia.

Genetic Factors in Aplastic Anemia

Higher incidence of HLA-DR2 in patients and polymorphisms in enzymes that metabolize benzene increase susceptibility.

Immune Mechanisms in Aplastic Anemia

Autoimmune destruction of hematopoietic stem cells is suggested by elevated cytotoxic T lymphocytes and cytokine production.

Immune Suppressive Therapy (IST)

A treatment for aplastic anemia involving antithymocyte globulin and cyclosporine.

Hematopoietic Stem Cell Transplantation (BMT)

Curative treatment option for severe aplastic anemia, preferably from an HLA-matched sibling.

Chronic Infections Affecting Aplastic Anemia

Infections with Epstein-Barr virus, HIV, hepatitis, and parvovirus B19 can lead to acquired aplastic anemia.

Fanconi Anemia

A chromosome instability disorder with aplastic anemia, physical abnormalities, and cancer susceptibility.

Symptoms of Fanconi Anemia

Pancytopenia, physical malformations, increased cancer risk including leukemia.

Diagnostics for Fanconi Anemia

Involves chromosomal breakage analysis after exposure to DNA cross-linking agents.

Dyskeratosis Congenita

A rare inherited syndrome characterized by mucocutaneous abnormalities and premature bone marrow failure.

Clinical Presentation of Dyskeratosis Congenita

Triad of abnormal skin pigmentation, dystrophic nails, and oral leukoplakia.

Laboratory Findings in Dyskeratosis Congenita

Pancytopenia and short telomeres, identified through genetic testing.

Shwachman-Bodian-Diamond Syndrome

A multisystem disorder linked with pancreatic insufficiency and cytopenias.

Symptoms of Shwachman-Bodian-Diamond Syndrome

Neutropenia, failure to thrive, and skeletal abnormalities.

Congenital Dyserythropoietic Anemias (CDAs)

A group of rare disorders characterized by ineffective erythropoiesis and distinctive dysplastic changes in bone marrow.

Pure Red Cell Aplasia (PRCA)

A rare disorder with selective and severe decrease in erythroid precursors.

Primary PRCA

May be idiopathic or associated with autoimmune conditions.

Secondary PRCA

Associated with underlying conditions such as thymoma or infections.

Diamond-Blackfan Anemia (DBA)

A congenital erythroid hypoplastic disorder characterized by macrocytic anemia and reticulocytopenia, usually evident in early infancy.

Laboratory Findings in DBA

Severe macrocytic anemia, normal WBCs, and hypoplasia of erythroid cells with normal myeloid line.

Chronic Kidney Disease and Anemia

Anemia is common in CKD due to inadequate erythropoietin production and chronic inflammation.

Management of Anemia in CKD

Includes iron supplementation and erythropoiesis-stimulating agents (ESAs).

Functional Iron Deficiency (FID)

Occurs when the bone marrow cannot release enough iron for erythropoiesis despite adequate iron stores.

Risk Factors for Hemolytic Anemia

Autoimmune disorders, certain drugs, and genetic predispositions can contribute.

Bone Marrow Examination

Used to assess hematological abnormalities; in aplastic anemia, shows hypocellularity with minimal dysplasia.

Hormonal Factors in Bone Marrow Failure

Decrease in hematopoietic growth factors leads to insufficient stimulation of bone marrow.

Cytogenetic Abnormalities in Aplastic Anemia

Common abnormalities include monosomy 7 and trisomy 8 detected by karyotype analysis.

Transfusion Considerations in Aplastic Anemia

Platelets should not be transfused unless the patient is bleeding, especially when counts are below 10,000/mL.

Symptoms of Thrombocytopenia

Includes petechiae, bruising, and mucosal bleeding.

Symptoms of Neutropenia

Increased risk of life-threatening infections, particularly bacterial and fungal.

Automimmune Mechanisms in Aplastic Anemia

Elevated T lymphocytes and cytokine production suggesting an autoimmune reaction against hematopoietic cells.

Differentiation of Aplastic Anemia from Other Causes

Requires assessment for inherited syndromes due to differing treatments and prognoses.

Treatment and Prognosis Overview

Initial management includes identifying causative agents and offering hematopoietic stem cell transplantation.

Long-term Complications in Aplastic Anemia

Include risks of developing myelodysplastic syndrome (MDS) and leukemia.

HLA Matching in Bone Marrow Transplantation

HLA-matched donors provide the best outcomes for bone marrow transplantation.

Use of Eltrombopag in Aplastic Anemia

A thrombopoietin mimetic that shows promise when added to standard treatment.

Epidemiology of Fanconi Anemia

Higher prevalence in Ashkenazi Jews and South African Africaners.

MDS and Aplastic Anemia

MDS can present similarly to aplastic anemia; differentiation is crucial for proper treatment.

Role of Cytokines in Bone Marrow Failure

Increased levels of certain cytokines can inhibit hematopoiesis and enhance apoptosis.

Physical Malformations in Fanconi Anemia

Common anomalies include skeletal defects, pigmentation issues, and organ malformations.

Importance of Transfusion Management

Judicious use of transfusions is important to avoid complications such as alloimmunization.

Environmental Factors in Aplastic Anemia

Exposure to toxins such as benzene and certain medications can trigger secondary aplastic anemia.

Familial Trends in Aplastic Anemia

Some forms of aplastic anemia can be hereditary; genetic assessment may be warranted.

Reticulocyte Analysis

Used to assess the bone marrow's ability to produce red blood cells, with low counts indicative of aplastic anemia.

Generalized Symptoms of Anemia

Common symptoms include fatigue, pallor, weakness, and shortness of breath.

Role of Adjunctive Therapies

Supportive care including antibiotics, antifungals, and growth factors enhances patient outcomes.

Volatile Substances and Aplastic Anemia

Exposure to certain chemicals has been linked to increased incidence of acquired aplastic anemia.

Identification of Candidate Antigens

Antigens from stem cells that may trigger autoimmune responses are being researched.

Genetic Screening in Aplastic Anemia

Testing for key gene mutations can clarify the diagnosis and guide therapy.

Causative Drug Classes for Aplastic Anemia

Includes cytotoxic agents, nonsteroidal anti-inflammatory drugs, and certain antibiotics.

Chronic Inflammatory States and Anemia

Conditions such as rheumatoid arthritis can contribute to anemia of chronic disease.

Mechanisms of Aplastic Anemia Evolution

Environmental insults can contribute to stem cell injury, leading to disease onset.

BMT Outcomes in Aplastic Anemia

Outcomes improve dramatically with younger patients and matched donors.

Monitoring Patients during IST

Regular assessment for response and complications is vital during immunosuppressive therapy.

Peripheral Blood Film Analysis

Helps identify abnormal cell types and further assess hematological disorders.

Clinical Trials in Aplastic Anemia

Ongoing research for novel therapies continues to improve management strategies.

Ethnic Variability in Aplastic Anemia Incidence

Different rates of disease manifestation across populations may suggest genetic influences.

Comparison of Acquired and Inherited Aplastic Anemia

Insight into differing prognoses and responses to treatment between the two categories.

Psychosocial Impact of Bone Marrow Failure

Patients may face mental health challenges due to chronic illness and treatment demands.

Impact of Age on Aplastic Anemia Prognosis

Prognosis often worsens with increasing age and declining overall health status.

Statistical Outcomes for BMT

Data shows improved survival rates for younger patients post-transplant.

Epidemiological Studies on Aplastic Anemia

Research often highlights variations in incidence based on geographic or environmental factors.

Infections Precipitating Aplastic Anemia

Viral infections can provoke acute episodes, necessitating careful monitoring.

Role of stem cell genetics in treatment

Understanding genetic predispositions can lead to personalized treatment plans.

Therapy Adjustments in Poor Responders

Patients not responding to initial therapies may require alternative approaches or further evaluation.

Crisis Management in Aplastic Anemia

Rapid intervention is critical during acute crises to prevent mortality.

Cytopenias in Multiple Hematological Disorders

Differentiating features of various hematological disorders can guide diagnosis.

Mechanisms of Ineffective Erythropoiesis

Defects in erythroid progenitor cells can lead to insufficient RBC production.

Clinical Presentation Timing of Aplastic Anemia

Age of onset can vary considerably depending on whether the condition is inherited or acquired.

Abnormal Bone Marrow Cellularity

Bone marrow in aplastic anemia exhibits severe hypocellularity and minimal dysplasia.

Potential Carcinogenic Factors

Chronic exposure to certain environmental agents may elevate cancer risks in hematological conditions.

Considerations in Pediatric Aplastic Anemia

Pediatric patients often have different response rates and treatment considerations than adults.

Influence of ESLD on Anemia

Patients with end-stage liver disease may exhibit atypical anemia patterns.

Industrial Exposure and Hematological Risks

Certain industrial environments pose risks for developing various forms of bone marrow failure.

Support Needs in Chronic Bone Marrow Failure

Patients require holistic support encompassing medical, psychological, and social aspects.

Genetics of Inherited Bone Marrow Failure Syndromes

Understanding specific gene mutations aids in diagnosis and management.

Histological Characteristics of Aplastic Anemia

Verifying the absence of immature cells and diagnosing hypocellularity is key.

Interventions for Chronic Anemia

Managing chronic anemia involves treating underlying conditions and symptomatic support.

Neutrophil Count Changes

Important indicator of bone marrow function and response to treatment in aplastic anemia.

Paroxysmal Nocturnal Hemoglobinuria

A hematologic condition sometimes overlapping with aplastic anemia that can affect prognosis.

Potential Risk from Blood Transfusions

Transfusion-related complications can include iron overload and alloimmunization.

Involvement of Genetic Counseling

Important for families affected by inherited blood disorders.

Influence of Viral Infections on Hematopoiesis

Specific viral infections can lead to significant impairments in blood cell production.

Effects of Environmental Toxins

Chronic exposure can lead to higher risks of developing bone marrow failure.

Bone Marrow Failure

Reduction or cessation of blood cell production affecting one or more cell lines.

Pancytopenia

Decreased numbers of circulating red blood cells (RBCs), white blood cells (WBCs), and platelets.

Aplastic Anemia

A rare but potentially fatal bone marrow failure syndrome characterized by pancytopenia, reticulocytopenia, and hypocellular marrow.

Idiopathic Aplastic Anemia

A type of acquired aplastic anemia with unknown cause.

Secondary Aplastic Anemia

A type of acquired aplastic anemia associated with identified causes such as drugs or infections.

Incidence of Aplastic Anemia

Approximately 1 in 500,000 in North America and Europe; higher in Asia.

Etiology of Aplastic Anemia

Includes exposure to drugs, chemicals, radiation, infections, and autoimmune mechanisms.

Mutations in Aplastic Anemia

Result in diminished hematopoietic stem cell function and may be inherited or acquired.

Chronic Neutropenia

Persistent low levels of neutrophils that increase the risk of infections.