Chronic myeloid leukemia (CML) is classified in ICD-10 under code C92.1, “chronic myeloid leukemia, BCR/ABL-positive.” In the US clinical modification (ICD-10-CM), a fifth character records disease status: C92.10 when remission has not been achieved, C92.11 when the patient is in remission, and C92.12 at relapse. This article takes a comprehensive look at chronic myeloid leukemia and its ICD-10 classification, and at the biology, diagnosis, and treatment that sit behind the code.
What Is Chronic Myeloid Leukemia?
Chronic myeloid leukemia is a cancer of the blood-forming stem cells in the bone marrow. It belongs to the family of myeloproliferative neoplasms, conditions in which the marrow overproduces one or more types of blood cell. In CML the main excess is of granulocytes, a type of white blood cell, at every stage of maturity.
Unlike acute leukemias, CML usually develops slowly. Many people have few or no symptoms at first, and the disease is often picked up on a routine blood test. Without treatment, however, it tends to progress over years to a more aggressive phase.
The disease is defined by one genetic change. An exchange of material between chromosomes 9 and 22, written t(9;22), creates a shortened chromosome 22 known as the Philadelphia chromosome. This joins two genes, BCR and ABL1, into a BCR::ABL1 fusion gene. Its protein is a tyrosine kinase that is permanently switched on, driving uncontrolled cell growth. The Philadelphia chromosome is found in about 95% of cases, and the remainder carry the fusion gene through more complex rearrangements.
ICD-10 Classification of CML
ICD-10 codes are used worldwide for medical records, statistics, and insurance claims. Choosing the right code depends on confirming the disease type and its current status. The table below shows the main codes relevant to CML and conditions that are often confused with it.
| Code | Description | Coding note |
|---|---|---|
| C92.1 | Chronic myeloid leukemia, BCR/ABL-positive | Standard code for typical CML |
| C92.10 | CML, not having achieved remission | ICD-10-CM; includes new diagnoses and treatment failure |
| C92.11 | CML, in remission | ICD-10-CM; documented remission |
| C92.12 | CML, in relapse | ICD-10-CM; return of disease after remission |
| C92.2 | Atypical chronic myeloid leukemia, BCR/ABL-negative | A separate disease that lacks the fusion gene |
| C93.1 | Chronic myelomonocytic leukemia | Different disease; not a CML code |
The newer ICD-11 system uses a different structure, but ICD-10 remains widely used in clinical and billing settings. The important point for coders is that “CML” in the notes should be backed by documentation of BCR::ABL1 positivity. If the fusion gene is absent, the diagnosis is not typical CML.
Documentation tips for accurate coding
- Record the genetics: note the BCR::ABL1 result from FISH or PCR, not just the blood count findings.
- Record the phase: chronic or blast phase affects treatment and should be clear in the notes, even though ICD-10 does not code it separately.
- Record remission status: the choice between C92.10, C92.11, and C92.12 depends on the physician documenting remission or relapse explicitly.
- Avoid assumptions: a coder should not infer remission from a normal blood count alone; it must be stated by the treating clinician.
Causes, Risk Factors, and Phases
For almost all patients, the Philadelphia chromosome arises by chance during a person’s lifetime. It is not inherited and cannot be passed to children. The best-established risk factor is high-dose exposure to ionizing radiation. CML is most often diagnosed in middle-aged and older adults and is slightly more common in men, but it can occur at any age.
CML has traditionally been described in three phases:
- Chronic phase: where most patients are diagnosed. Blood counts are abnormal, but the cells still mature and work fairly normally.
- Accelerated phase: rising blast counts, worsening blood counts, and new genetic changes. The most recent WHO classification drops this phase and instead flags high-risk features, while other systems still use it.
- Blast phase: behaves like acute leukemia, with 20% or more blasts in the blood or marrow under WHO criteria.
Symptoms and Diagnosis
When symptoms occur, they commonly include fatigue, night sweats, weight loss, and a feeling of fullness or discomfort under the left ribs from an enlarged spleen. Bruising, bleeding, bone pain, and fevers are more typical of advanced disease.
Diagnosis usually follows this pathway:
- Complete blood count: typically a high white cell count, often with raised basophils and sometimes a high platelet count.
- Blood film: shows granulocytes at all stages of development.
- Bone marrow aspiration and biopsy: confirms the phase by counting blasts and allows full chromosome analysis.
- Cytogenetics or FISH: detects the Philadelphia chromosome or the BCR::ABL1 fusion.
- Quantitative PCR: measures BCR::ABL1 transcript levels and sets the baseline for monitoring.
Treatment and Monitoring
Tyrosine kinase inhibitors (TKIs) transformed CML from a fatal disease into a chronic condition for most patients. They block the overactive BCR::ABL1 protein. First-line options include imatinib, dasatinib, nilotinib, and bosutinib. Ponatinib and asciminib are used for resistance, intolerance, or specific mutations such as T315I.
Response is tracked by PCR on the International Scale. A major molecular response means BCR::ABL1 has fallen to 0.1% or less, and deeper responses are measured beyond that. In my practice, taking the tablets consistently is the single most important thing patients control, because missed doses are a common reason for losing response.
Some patients with a sustained deep molecular response can try stopping their TKI under close monitoring, called treatment-free remission. Those who relapse usually respond again when the drug is restarted. Stem cell transplantation is now reserved mainly for blast phase or disease that fails several TKIs.
Research continues into better options for resistant disease and into which patients can safely stop treatment. For a broader view of related conditions, see our leukemia guide.
Frequently Asked Questions
What is the ICD-10 code for chronic myeloid leukemia?
The code is C92.1, chronic myeloid leukemia, BCR/ABL-positive. In ICD-10-CM, C92.10, C92.11, and C92.12 add whether the disease is not in remission, in remission, or in relapse.
Is CML curable?
Most people in chronic phase who respond well to TKIs have a life expectancy close to that of the general population. Some achieve treatment-free remission. Stem cell transplant can be curative but carries significant risks, so it is not first-line.
Is chronic myeloid leukemia hereditary?
No. The Philadelphia chromosome is acquired in the marrow during life, not inherited, so family members are not at increased risk.
How is atypical CML different?
Atypical CML (C92.2) looks similar under the microscope but lacks the BCR::ABL1 fusion gene. It does not respond to TKIs in the same way and is managed differently.
Key Takeaways
- CML is coded C92.1 in ICD-10, with status subcodes C92.10, C92.11, and C92.12 in ICD-10-CM.
- The BCR::ABL1 fusion gene, usually from the Philadelphia chromosome, defines the disease.
- Diagnosis combines blood counts, marrow examination, and genetic testing.
- TKIs are the mainstay of treatment, with PCR monitoring guiding care.
