Chronic myelomonocytic leukemia

Classification according to ICD-10
C93.10	Chronic myelomonocytic leukemia: Without indication of complete remission ICD-O 9945/3
C93.11	Chronic myelomonocytic leukemia: In complete remission ICD-O 9960/1
ICD-10 online (WHO version 2019)

The chronic myelomonocytic leukemia (CMML) is a malignant disease of the hematopoietic system. It used to be counted among the myelodysplastic syndromes (MDS), but has some aspects similar to myeloproliferative neoplasia (MPN), e.g. B. chronic myeloid leukemia (CML), so that it is listed in the 2008 WHO classification of hematological neoplasms as "MDS / MPN".

Incidence, clinical manifestations, symptoms

Exact numbers on the incidence do not exist. However, CMML is certainly a rare disease with an estimated 1–3 new cases per year and 100,000 people. It occurs almost exclusively in old age and the mean age of onset is around 55–65 years. Around half of the patients have normal or even low white blood cell counts at the time of diagnosis . The other half has an increased white blood cell count. However, an absolute increase in monocytes (> 1000 / µl) in the peripheral blood is always detectable (diagnostic criterion, see below). Splenomegaly (enlarged spleen) and / or hepatomegaly (enlarged liver) are common (but not always) found. The patient's complaints are usually relatively uncharacteristic: unwanted weight loss , general weakness ( fatigue ), fever , night sweats , etc. U. bleeding tendency (with thrombopenia ). The diagnosis is ultimately made on the basis of clinical manifestations, the differential blood count (taken several times at long intervals) and a bone marrow examination .

Definition of disease, causes

CMML is a clonal disease that originates from a genetically modified bone marrow stem cell. The descendants of these malignant, degenerate stem cells spread in the bone marrow, suppress healthy blood formation there and finally also appear in the peripheral blood. The causes and nature of the genetic changes in CMML are so far poorly understood. Some genetic changes have been identified, but these are only found in a subset of patients.

WHO diagnostic criteria

A panel of experts from the World Health Organization (WHO) has formulated the following 4 criteria for the diagnosis of CMML:

• Monocytosis in peripheral blood> 1 × 10 ⁹ / l or> 1000 / µl (normal value <800 / µl)
• less than 20% blasts (= myeloblasts, monoblasts and promonocytes) in the bone marrow
• no evidence of the BCR-ABL oncogene or Philadelphia chromosome
• Dysplasias in one or more rows of myelopoiesis ( erythropoiesis , granulopoiesis , megakaryopoiesis )

All 4 criteria must be met for a diagnosis to be made. If only 3 of these 4 criteria are met, other diagnoses usually result:

• if a Philadelphia chromosome or BCR-ABL is detectable, the diagnosis is CML rather than CMML
• if the proportion of monocytes is below 1000 / µl, but the other criteria are met, the diagnosis of another myelodysplastic syndrome would be more likely
• if there are more than 20% blasts in the bone marrow , the diagnosis is " acute myeloid leukemia ".

However, in its diagnostic criteria, the WHO conceded that the diagnosis of CMML can also be made if no dysplasia can be detected, but the other criteria are met and, in particular, the monocytosis has existed for at least 3 months without an apparent external cause.

The WHO classification of 2001 and 2008 attempted an even finer division into two subgroups:

• CMML-1 : less than 5% blasts in peripheral blood and less than 10% blasts in bone marrow
• CMML-2 : 5–19% blasts in peripheral blood and 10–19% blasts in bone marrow.

In addition, it was suggested to add the annex "with eosinophilia" if the eosinophil count in the peripheral blood is> 1500 / µl (i.e. CMML-1 or CMML-2 with eosinophilia).

A retrospective evaluation of the Düsseldorf MDS registry showed that the two groups CMML-1 and CMML-2 have different prognoses with regard to overall survival and the risk of disease progression towards acute myeloid leukemia. The classification of the CMML remains in flux and will certainly experience further changes in the future.

therapy

Azacitidine is approved for chronic myelomonocytic leukemia with 10-29% bone marrow blasts without myeloproliferative disorder.

Literature and Sources

• SH Swerdlow, E. Campo, NL Harris, ES Jaffe, SA Pileri, H. Stein, J. Thiele, JW Vardiman (Eds.): WHO classification of Tumors of Haemopoietic and Lymphoid Tissues . IARC Press, Lyon 2008, ISBN 978-92-832-2431-0 (WHO 2008 classification)
• E. Jaffe, NL Harris, H. Stein, JW Vardiman (Eds.): Pathology and Genetics of Tumors of Haemopoietic and Lymphoid Tissues . IARC Press, Lyon 2001 (WHO 2001 classification)

Web links

• MDS-Krankheit.de Extensive information for patients
• Vidaza.de Extensive information for healthcare professionals and patients
• Lifeline: Chronic Myelomonocytic Leukemia

Individual evidence

1. ↑ U. Germing, C. Strupp, S. Knipp, A. Kuendgen, A. Giagounidis, B. Hildebrandt, C. Aul, R. Haas, N. Gattermann, JM Bennett: Chronic myelomonocytic leukemia in the light of the WHO proposals . In: Haematologica . 2007; 92, pp. 974-977. PMID 17606449 .
2. ↑ Prescribing Information Vidaza . March 2016.

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !