Acute monocytic leukemia
| Acute monocytic leukemia | |
|---|---|
| Classification and external resources | |
| Specialty | Hematology and oncology |
| ICD-10 | C93.0 |
| ICD-9-CM | 206.0 |
| Patient UK | Acute monocytic leukemia |
| MeSH | D007948 |
Acute monocytic leukemia (AMoL, or AML-M5)[1] is considered a type of acute myeloid leukemia.
Diagnosis
In order to fulfill World Health Organization (WHO) criteria for AML-5, a patient must have greater than 20% blasts in the bone marrow, and of these, greater than 80% must be of the monocytic lineage. A further subclassification (M5a versus M5b) is made depending on whether the monocytic cells are predominantly monoblasts (>80%) (acute monoblastic leukemia) or a mixture of monoblasts and promonocytes (<80% blasts). Monoblasts can be distinguished by having a roughly circular nucleus, delicate lacy chromatin, and abundant, often basophilic cytoplasm. These cells may also have pseudopods. By contrast, promonocytes have a more convoluted nucleus, and their cytoplasm may contain metachromatic granules. Monoblasts are typically MPO-negative and promonocytes are MPO variable. Both monoblasts and promonocytes stain positive for non-specific esterase (NSE), however NSE may often be negative.
Immunophenotypically, M5-AML variably express myeloid (CD13, CD33) and monocytic (CD11b, CD11c) markers. Cells may aberrantly express B-cell marker CD20 and the NK marker CD56. Monoblasts may be positive for CD34.
Causes
M5 is associated with characteristic chromosomal abnormalities, often involving Chromosome 11 at 11q23 or t(9;11) affecting the MLL locus, however the MLL translocation is also found in other AML subtypes. MLL is believed to be prognostically unfavorable in AML-M5 compared to other genetic alterations involving MLL such as t(9;11). The t(8;16) translocation in MLL is associated with hemophagocytosis.
Secondary leukaemia, which may include AML-M5, has been associated with exposure to epipodophyllotoxins, such as etoposide.[2]
Treatment
AML-M5 is treated with intensive chemotherapy (such as anthracyclines) or with bone marrow transplantation.
References
External links
- Images at Nagoya University
- Image at hmds.org.uk
- Histology at University of Virginia
- Overview at Marist College
