Leukemia ICD-10 Codes: Complete Guide by Type

If you’re looking up leukemia ICD-10 codes, here’s the quick answer: leukemia falls under codes C91–C95 in the ICD-10-CM system, with each major type getting its own category. C91 covers lymphoid leukemia, C92 covers myeloid leukemia, C93 is monocytic leukemia, C94 handles other specified leukemias, and C95 is reserved for leukemia of unspecified cell type.

But just knowing the code range isn’t enough. Each category breaks down further by acuity (acute vs. chronic) and remission status — and picking the wrong code can trigger claim denials or misrepresent a patient’s condition. Below is a comprehensive medical overview of every major leukemia ICD-10 code, what each one means clinically, and how to use them correctly.

Because acuity drives both coding and care decisions, it helps to see how chronic leukemia treatment approaches differ by subtype, since remission status documented in the chart flows directly from those clinical pathways.

Complete Leukemia ICD-10 Code Table

Key point: The 5th character matters. A “0” at the end typically means “not having achieved remission” (or “failed to achieve remission” or “with relapse”), while “1” indicates the patient is in remission. Getting this right affects treatment authorization and survivorship coding.

The Four Major Leukemia Types Explained

Acute Lymphoblastic Leukemia (ALL) — C91.0x

Acute lymphoblastic leukemia is the most common childhood cancer, accounting for roughly 75–80% of pediatric leukemia cases. The 5-year survival rate in children now exceeds 90%, though adults fare worse at around 30–40%. ALL is characterized by rapid proliferation of immature lymphoid cells (lymphoblasts) that crowd out normal blood cell production.

Diagnosis requires ≥20% lymphoblasts in the bone marrow. Flow cytometry distinguishes B-cell ALL (more common, ~85% of cases) from T-cell ALL, which matters for treatment selection and prognosis.

Acute Myeloid Leukemia (AML) — C92.0x

Acute myeloid leukemia is the most common acute leukemia in adults, with a median age at diagnosis of 68 years. About 20,000 new cases are diagnosed annually in the United States. AML carries a 5-year survival rate of approximately 30% overall, though outcomes vary dramatically by molecular subtype.

The ICD-10 system gives AML several subcodes: C92.4 for acute promyelocytic leukemia (APL, which has a cure rate exceeding 90% with ATRA-based therapy), C92.5 for acute myelomonocytic leukemia, and C92.6 for acute myeloid leukemia with 11q23-abnormality.

Chronic Lymphocytic Leukemia (CLL) — C91.1x

Chronic lymphocytic leukemia is the most prevalent leukemia in Western countries, with roughly 20,000 new U.S. cases per year. Median age at diagnosis is 70, and many patients are discovered incidentally through routine blood work showing lymphocytosis (>5,000 monoclonal B-lymphocytes/µL).

CLL can be indolent for years. The Rai and Binet staging systems guide treatment decisions — many early-stage patients follow a “watch and wait” approach with no immediate therapy needed.

Chronic Myeloid Leukemia (CML) — C92.1x

Chronic myeloid leukemia accounts for about 15% of adult leukemias. It’s defined by the Philadelphia chromosome — a translocation between chromosomes 9 and 22 that creates the BCR-ABL1 fusion gene. This is why the ICD-10 code specifically states “BCR/ABL-positive.”

CML transformed from a near-death sentence to a manageable chronic disease after the introduction of imatinib (Gleevec) in 2001. Patients achieving deep molecular response now have near-normal life expectancy.

How Leukemia Is Diagnosed

Diagnosis follows a predictable sequence, and each step informs both the clinical picture and the correct ICD-10 code assignment:

• Complete blood count (CBC): The first flag — may show WBC counts ranging from very low (<1,000/µL) to extremely elevated (>100,000/µL), along with anemia (hemoglobin <10 g/dL) and thrombocytopenia (platelets <100,000/µL)
• Peripheral blood smear: Reveals circulating blasts in acute leukemias or mature-appearing but clonal lymphocytes in CLL
• Bone marrow biopsy: The gold standard — determines blast percentage, cellularity, and architecture
• Flow cytometry: Identifies cell surface markers (e.g., CD19, CD20 for B-cell; CD3, CD7 for T-cell) to classify lineage
• Cytogenetics and FISH: Detects chromosomal abnormalities like t(9;22) in CML or t(15;17) in APL
• Molecular testing (PCR/NGS): Identifies mutations in FLT3, NPM1, TP53, IDH1/2, and others that guide targeted therapy

ICD-10 Coding Tips That Prevent Denials

Coders and clinicians frequently make avoidable errors with leukemia ICD-10 codes. Here’s what to watch for:

• Never default to C95 (unspecified) when documentation supports a specific type. Payers increasingly reject unspecified codes when the clinical workup clearly identifies the subtype.
• Remission status must be documented by the treating physician. Don’t assume remission — look for explicit language in the progress notes.
• “History of” leukemia uses Z85.6 (personal history of leukemia), not the active C91–C95 codes. This applies once treatment is complete and the patient is considered cured.
• Relapsed leukemia goes back to the active disease code with the “not having achieved remission” 5th character, not a Z code.

When to See a Doctor

Seek medical attention promptly if you experience any combination of these symptoms lasting more than two weeks:

• Persistent, unexplained fatigue not improved by rest
• Recurrent fevers or infections
• Unusual bruising or bleeding (nosebleeds, bleeding gums, petechiae)
• Unintentional weight loss exceeding 5% of body weight
• Night sweats drenching your bedsheets
• Bone or joint pain without a clear cause

If you’ve already had blood work showing abnormal WBC, low hemoglobin, or low platelets, ask your doctor about a referral to a hematologist. Early evaluation can be the difference between catching something treatable and missing a narrow window.

Frequently Asked Questions

What is the ICD-10 code for leukemia, unspecified?

C95.9 is the code for leukemia, unspecified, not having achieved remission. However, this code should only be used when the documentation genuinely lacks information about the cell type. In practice, most cases should be coded more specifically under C91–C94 once diagnostic workup is complete.

Does the ICD-10 code change when a patient goes into remission?

Yes. Each leukemia code has a remission variant. For example, AML actively being treated is C92.00, while AML in remission is C92.01. The physician must explicitly document remission status for the coder to assign the remission code.

What’s the difference between C91.0 and C91.1?

C91.0 codes acute lymphoblastic leukemia (ALL), while C91.1 codes chronic lymphocytic leukemia (CLL). Despite both being lymphoid malignancies, they are completely different diseases — ALL is aggressive and requires immediate treatment, while CLL is often indolent and may not need treatment for years.

Is there an ICD-10 code for pre-leukemia or MDS?

Myelodysplastic syndromes (MDS), sometimes called “pre-leukemia,” are coded under D46 — not the C91–C95 leukemia codes. If MDS transforms to AML (which happens in roughly 30% of cases), the coding switches to the appropriate C92 code at that point.

Which leukemia ICD-10 code is used most often?

Based on disease prevalence, C91.1 (CLL) and C92.0 (AML) are among the most commonly used leukemia codes in adult populations. In pediatric settings, C91.0 (ALL) dominates. The specific “not in remission” vs. “in remission” variants each see heavy use depending on treatment phase.