Agranulocytosis
|
WikiDoc Resources for Agranulocytosis |
|
Articles |
|---|
|
Most recent articles on Agranulocytosis Most cited articles on Agranulocytosis |
|
Media |
|
Powerpoint slides on Agranulocytosis |
|
Evidence Based Medicine |
|
Clinical Trials |
|
Ongoing Trials on Agranulocytosis at Clinical Trials.gov Trial results on Agranulocytosis Clinical Trials on Agranulocytosis at Google
|
|
Guidelines / Policies / Govt |
|
US National Guidelines Clearinghouse on Agranulocytosis NICE Guidance on Agranulocytosis
|
|
Books |
|
News |
|
Commentary |
|
Definitions |
|
Patient Resources / Community |
|
Patient resources on Agranulocytosis Discussion groups on Agranulocytosis Patient Handouts on Agranulocytosis Directions to Hospitals Treating Agranulocytosis Risk calculators and risk factors for Agranulocytosis
|
|
Healthcare Provider Resources |
|
Causes & Risk Factors for Agranulocytosis |
|
Continuing Medical Education (CME) |
|
International |
|
|
|
Business |
|
Experimental / Informatics |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Daniel A. Gerber, M.D. [2]
Overview
Agranulocytosis is a hematological disorder characterized by the acute-onset of severe neutropenia. Neutrophils - a subset of white blood cell - normally make up 50-70% of circulating white blood cells and serve as the primary defense against infections. Hence, patients with neutropenia are more susceptible to infections, mainly bacterial, and without prompt medical attention, the condition is often life-threatening. Similar to severe neutropenia in the setting of infection, cases related to cytotoxic chemotherapy, hematopoietic stem cell transplant, or other causes of bone marrow suppression are considered a medical emergency.
Agranulocytosis is defined as severe neutropenia with an absolute neutrophil count (ANC) <500 cells/microliter.
While agranulocytosis technically refers to a reduction in all cells in the leukocyte lineage (neutrophils, eosinophils, and basophils), the vast majority of cases refer to neutropenia as neutrophils constitute the majority of leukocytes and the primary defense against infection.
Historical Perspective
Agranulocytosis, or severe neutropenia, was first noted around the start of the 20th century on review of blood cell differentials described in patients with lupus, other autoimmune disorders, and with various drug toxicities.[1]
Classification
Agranulocytosis is often used interchangeably with severe neutropenia. Calculated based on complete blood count differential, agranulocytosis is loosely defined as an absolute neutrophil count (ANC) less than 500, 200, or 100 cells per microliter, with mild and moderate neutropenia defined below.[2] The ANC is calculated by multiplying the total white blood cell (WBC) count by the percentage of neutrophils (including both mature neutrophils and band forms).
- Mild Neutropenia: ANC 1,000-1500 cells/microliter
- Moderate Neutropenia: ANC 500-1000 cells/microliter
- Severe Neutropenia or Agranulocytosis: ANC <500 cells/microliter
This distinction is important diagnostically and prognostically. Patients with ANC <500 cells/microliter are at a markedly increased risk for severe infections and those <100 cells/microliter have just over a 3-fold increased risk of mortality (10% vs. 3%; p <0.001).[2] The ANC is calculated by multiplying the total white blood cell (WBC) count by the percentage of neutrophils (including both mature neutrophils and band forms). Importantly, due to severely limited neutrophil activity an inflammatory response, these patients may present with a fever absent additional localizing signs of infection.
Pathophysiology
Agranulocytosis develops as a result of one of the three following mechanisms:
- Impaired granulocyte production
- Aplastic anemia
- Hematologic malignancy with bone marrow infiltration
- Myelosuppressive chemotherapy or other medications that are toxic to the bone marrow
- Nutritional deficiencies
- Margination: the process by which free flowing blood cells are signaled to adhere to the endothelial wall and exit circulation.
- Splenic sequestration and destruction
- Adherence to the vascular endothelium
- Accelerated peripheral destruction[3]
Causes
Agranulocytosis is most commonly attributed to malignancy and idiosyncratic drug reactions.
Malignancy is often associated with neutropenia, due to impaired production from myelodysplastic syndromes and hematological malignancies with bone marrow infiltration, hemolysis and impaired production from cytotoxic chemotherapy, and antibody-mediated destruction of neutrophils.
More than 125 drugs have been identified as causative agents of agranulocytosis. The following medications account for over 50% of definitive cases: antiepileptics, antithyroid drugs (carbimazole, methimazole, propylthiouracil), antibiotics (penicillin, chloramphenicol, co-trimoxazole, dapsone), cytotoxic chemotherapeutics, arsenic, gold, NSAIDs (indomethacin, naproxen, phenylbutazone, metamizole), antihelminths (mebendazole, albendazole), allopurinol, mirtazapine, and the antipsychotic clozapine.[4][5][6]
Immunodeficiencies are frequently associated with neutropenia (38% in Hyper IgM syndrome, 12% in CVID, and 7% in X-linked agammaglobulinemia) as are autoimmune disorders including up to 50% of patients with systemic lupus erythematosus, yet with lower overall prevalence. While rheumatoid arthritis infrequently presents with neutropenia, agranulocytosis can develop in the setting of large granular lymphocyte (LGL) leukemia or Felty's syndrome.[7]
Causes by Organ System
Differentiating [Disease] from Other Diseases
Agranulocytosis is a laboratory diagnosis based off of the complete blood count differential, however the differential diagnosis for the etiology of neutropenia and agranulocytosis is quite important as these patients can deteriorate rapidly without appropriate treatment.
Consider the following differential when evaluating a patient with agranulocytosis:
- Drug-induced: An idiosyncratic (dose-independent) reaction. Accounts for 65-75% of all cases of agranulocytosis in the United States. More commonly presents with isolated neutropenia in the absence of anemia or thrombocytopenia.[8]
- Malignant: Typically, a dose-dependent reduction in neutrophils to cytotoxic chemotherapy, malignant infiltration of the bone marrow, or immune-mediated hemolysis. Often seen concurrently with severe anemia, thrombocytopenia, hepatosplenomegaly, and lymphadenopathy.
- Autoimmune: Antibody-mediated neutrophil destruction.[7]
Epidemiology and Demographics
Neutropenia is typically identified in at-risk patients undergoing cytotoxic chemotherapy or on other myelosuppressive medications. While some ethnicities have an unusually high prevalence of asymptomatic mild neutropenia (ANC 1,000-1500 cells/microliter) known as constitutional or benign ethnic neutropenia (BEN), these do not progress to agranulocytosis, do not increase the risk of infection, and present no additional risk in the setting of cytotoxic chemotherapy as these individuals have normal bone marrow neutrophil reserves.[9][10][11].
Immunodeficiencies are frequently associated with neutropenia (38% in Hyper IgM syndrome, 12% in CVID, and 7% in X-linked agammaglobulinemia) as are autoimmune disorders including up to 50% of patients with systemic lupus erythematosus, yet with lower overall prevalence. While rheumatoid arthritis infrequently presents with neutropenia, severe neutropenia can develop in the setting of large granular lymphocyte (LGL) leukemia or Felty's syndrome.[7]
Risk Factors
At-risk populations include the following:
- Medications[12]
- Cytotoxic chemotherapy
- Hematologic malignancies
- Autoimmune disorders
Screening
There are no routine screening recommendations for agranulocytosis. It is typically identified incidentally on routine blood work or while monitoring after cytotoxic therapy.[13]
Natural History, Complications, and Prognosis
Natural History
Neutropenia, and progression to agranulocytosis, occurs in either a dose-dependent or idiosyncratic process dependent upon the etiology. Neutropenia caused by cytotoxic chemotherapy or malignant bone marrow infiltration and failure is typically dose-dependent or related to tumor burden, as opposed to idiosyncratic - unpredictable, dose-independent, and typically immune-mediated - drug reactions.
Complications
Severe neutropenia or agranulocytosis warrant significant attention to any symptoms of infection, malignancy, or potentially contributing medications as infectious complications carry a mortality rate of up to 10%.[14]
Prognosis
While the prognosis for low risk neutropenia is excellent, with >90% probability of complete resolution without complications, high risk patients have >40% risk of serious complications. Risk stratification for patients with neutropenia is defined below.
Low risk: typically patients with solid tumors on chemotherapy plus the following:
- Anticipated neutropenia (ANC<500 cells/microliter) <7 days
- No significant hepatic or renal dysfunction
- No significant comorbidities**
- MASCC Risk Score >21 (PPV 91%, specificity 68%, sensitivity 71%)
High risk
- Anticipated neutropenia (ANC<500 cells/microliter) >7 days
- Significant hepatic or renal dysfunction
- Significant comorbidities**
- Disease progression
- MASCC Risk Score <21 (PPV 91%, specificity 68%, sensitivity 71%)
**Significant comorbidities: Hemodynamic instability, mucositis, GI symptoms, acute neurological changes, intravascular catheters, pulmonary infiltrates, or underlying chronic lung disease.
Diagnosis
Diagnostic Criteria
The diagnosis is made after a complete blood count, a routine blood test. The absolute neutrophil count in this test will be below 500, and can reach 0 cells/mm³. Other kinds of blood cells are typically present in normal numbers.
To formally diagnose agranulocytosis, other pathologies with a similar presentation must be excluded, such as aplastic anemia, paroxysmal nocturnal hemoglobinuria, myelodysplasia and leukemias. This requires a bone marrow examination that shows normocellular (normal amounts and types of cells) blood marrow with underdeveloped promyelocytes. These underdeveloped promyelocytes, if fully matured, would have been the missing granulocytes.
History and Symptoms
History of patients with agranulocytosis should focus on symptoms suggestive of malignancy, infection, or autoimmune disorders, and careful attention to identifying any new or recent medications. Some common infections can take an unexpected course in neutropenic patients; for example, formation of pus can be notably absent, as this requires circulating neutrophil granulocytes.[13] As a result, neutropenia and agranulocytosis may remain undetected until the patient develops secondary, and often severe, infections or sepsis.
Common symptoms include:
- Fever
- Frequent infections due to immunocompromization
- Unusual redness, pain, or swelling around a wound
- Mouth ulcers
- Diarrhea
- Burning sensation when urinating
- Sore throat
- Shortness of breath
- Shaking chills
Physical Examination
Agranulocytosis may be asymptomatic, or may clinically present with sudden fever, rigors and sore throat. Infection of any organ may be rapidly progressive (e.g., pneumonia, urinary tract infection). Septicemia may also progress rapidly.
Laboratory Findings
Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
In patients that have no symptoms of infection, management consists of close monitoring with serial blood counts, withdrawal of the offending agent (e.g., medication), and general advice on the significance of fever.
Transfusion of granulocytes would have been a solution to the problem. However, granulocytes live only ~10 hours in the circulation (for days in spleen or other tissue), which gives a very short-lasting effect. In addition, there are many complications of such a procedure.
Surgery
There are no surgical treatments for agranulocytosis. In patients' with neutropenic fever, surgical intervention may be necessary depending on the source of infection.
Prevention
Prevention of agranulocytosis is dependent upon avoiding certain medications or treatment of underlying conditions. Occasionally, when agranulocytosis is anticipated, such as in the setting of cytotoxic chemotherapy, recombinant G-CSF (granulocyte-colony stimulating factor) can be considered to speed myeloid reconstitution.
See also
References
- ↑ Dameshek W. (1944). "Leukopenia and Agranulocytosis". Oxford University Press. 1: 841–52. Text "NLM ID 39120200R" ignored (help)
- ↑ 2.0 2.1 Andersohn F, Konzen C, Garbe E. (2007). "Systematic review: agranulocytosis induced by nonchemotherapy drugs". Ann Internal Med. 146(9): 657–65. Text "PMID 17470834" ignored (help)
- ↑ Kumar, Vinay (2007). Robbins Basic Pathology (8 ed.). 441: Elsevier.
- ↑ Elisa Mari; Franco Ricci; Davide Imberti; Massimo Gallerani (June 2011). "Agranulocytosis: an adverse effect of allopurinol treatment". Italian Journal of Medicine. 5 (2): 120–3. doi:10.1016/j.itjm.2011.02.006.
- ↑ Diaz, Jaime (1996). How Drugs Influence Behavior. Englewood Cliffs: Prentice Hall. ISBN 0132815605.
- ↑ Andersohn F, Konzen C, Garbe E (May 2007). "Systematic review: agranulocytosis induced by nonchemotherapy drugs". Ann. Intern. Med. 146 (9): 657–65. doi:10.7326/0003-4819-146-9-200705010-00009. PMID 17470834.
- ↑ 7.0 7.1 7.2 Bucknall RC, Davis P, Bacon PA, Jones JV (2009). "Neutropenia in rheumatoid arthritis: studies on possible contributing factors". Ann Rheum Dis. 41 (3): 242–7. PMID 6979979.
- ↑ Andersohn F, Konzen C, Garbe E (May 2007). "Systematic review: agranulocytosis induced by nonchemotherapy drugs". Ann. Intern. Med. 146 (9): 657–65. doi:10.7326/0003-4819-146-9-200705010-00009. PMID 17470834.
- ↑ Shoenfeld Y, Alkan ML, Asaly A, Carmeli Y, Katz M (1988). "Benign familial leukopenia and neutropenia in different ethnic groups". Eur J Haematol. 41 (3): 273–7. PMID 3181399.
- ↑ Shoenfeld Y, Ben-Tal O, Berliner S, Pinkhas J (1985). "The outcome of bacterial infection in subjects with benign familial leukopenia (BFL)". Biomed Pharmacother. 39 (1): 23–6. PMID 4027348.
- ↑ Hsieh MM, Tisdale JF, Rodgers GP, Young NS, Trimble EL, Little RF (2009). "Neutrophil count in African Americans: lowering the target cutoff to initiate or resume chemotherapy?". J Clin Oncol. 28 (10): 1633–7. PMID 20194862.
- ↑ Andrès E, Zimmer J, Affenberger S, Federici L, Alt M, Maloisel F. (2006). "Idiosyncratic drug-induced agranulocytosis: Update of an old disorder". Eur J Intern Med. 17 (8): 529–35. Text "pmid 17142169" ignored (help)
- ↑ 13.0 13.1 Freifeld AG, Bow EJ, Sepkowitz KA, Boeckh MJ, Ito JI, Mullen CA, Raad II, Rolston KV, Young JA, Wingard JR; Infectious Diseases Society of America. (2011). "Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the infectious diseases society of america". Clin Infect Dis. 52 (4): e56–95. PMID 21258094.
- ↑ Andrès E, Maloisel F. (2008). "Idiosyncratic drug-induced agranulocytosis or acute neutropenia". Curr Opin Hematol. 15 (1): 15–21. PMID 18043241.