C93.1 Chronic myelomonocytic leukemia

Name of the Condition

• Chronic myelomonocytic leukemia
• ICD-10 Code: C93.1

Summary

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative neoplasm characterized by the overproduction of abnormal monocytes and myeloid cells in the bone marrow. This condition disrupts normal blood cell production, leading to cytopenias and potential organ infiltration. It is defined by persistent monocytosis (≥1×10⁹/L) and dysplasia in one or more myeloid lineages, with a variable clinical course that may resemble myelodysplastic syndromes or myeloproliferative neoplasms.

Causes

The development involves genetic mutations in hematopoietic stem cells, often including TET2, ASXL1, SRSF2, or RUNX1. These mutations drive uncontrolled proliferation and impaired differentiation of myeloid precursors. Secondary cases may arise from prior chemotherapy, radiation, or myelodysplastic syndromes, though de novo occurrences are more common.

Risk Factors

• Prior exposure to chemotherapy or radiation therapy
• Myelodysplastic syndromes or myeloproliferative neoplasms
• Advanced age (peak incidence in older adults)
• Male gender (slightly higher prevalence)
• Environmental exposures (e.g., benzene)

Symptoms

• Persistent fatigue or weakness
• Unexplained fever or night sweats
• Frequent infections
• Easy bruising or bleeding
• Bone or joint pain
• Abdominal discomfort due to enlarged spleen
• Weight loss without effort

Diagnosis

Diagnosis involves a physical examination, followed by blood tests to assess cell counts and abnormalities. A bone marrow biopsy confirms the presence of leukemic cells and dysplasia. Additional tests, such as flow cytometry or genetic analysis, may be used to identify specific mutations and support classification.

Treatment Options

Treatment depends on the patient’s risk stratification and symptoms. Options may include hypomethylating agents (e.g., azacitidine), targeted therapies, or supportive care (e.g., blood transfusions, antibiotics). Allogeneic stem cell transplantation may be considered for eligible patients.

Prognosis and Follow-Up

Prognosis varies based on risk factors, such as cytogenetics and blast count. Regular follow-up with blood counts and bone marrow assessments is essential to monitor disease progression. Complications like infection or transformation to acute leukemia may occur.

Complications

• Increased risk of infections due to impaired immune function
• Bleeding or bruising from low platelet counts
• Transformation to acute myeloid leukemia
• Organ infiltration (e.g., spleen enlargement)

Lifestyle & Prevention

No specific prevention strategies exist. Maintaining overall health, avoiding known environmental toxins, and adhering to recommended screening for high-risk individuals may help reduce risk.

When to Seek Professional Help

Seek medical attention for persistent symptoms like unexplained fatigue, fever, or bleeding. Prompt evaluation is important if symptoms worsen or new complications arise.

Tips for Medical Coders

Document the presence of monocytosis, dysplasia, and any genetic mutations to support the diagnosis. Ensure documentation aligns with the clinical criteria for CMML, including bone marrow findings and blood count abnormalities.