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C91.00 ICD-10-CM Code: Acute lymphoblastic leukemia not having achieved remission

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
2 inclusion terms · 1 Excludes1 · 4 Excludes2
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 8 · RxHCC V08 category 19

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 820 — LYMPHOMA AND LEUKEMIA WITH MAJOR O.R. PROCEDURES WITH MCC (MDC 17)
  • MS-DRG 821 — LYMPHOMA AND LEUKEMIA WITH MAJOR O.R. PROCEDURES WITH CC (MDC 17)
  • MS-DRG 822 — LYMPHOMA AND LEUKEMIA WITH MAJOR O.R. PROCEDURES WITHOUT CC/MCC (MDC 17)
  • MS-DRG 834 — ACUTE LEUKEMIA WITH MCC (MDC 17)
  • MS-DRG 835 — ACUTE LEUKEMIA WITH CC (MDC 17)
  • MS-DRG 836 — ACUTE LEUKEMIA WITHOUT CC/MCC (MDC 17)
  • MS-DRG 837 — CHEMOTHERAPY WITH ACUTE LEUKEMIA AS SECONDARY DIAGNOSIS OR WITH HIGH DOSE CHEMOTHERAPY AGENT WITH MCC (MDC 17)
  • MS-DRG 838 — CHEMOTHERAPY WITH ACUTE LEUKEMIA AS SECONDARY DIAGNOSIS WITH CC OR HIGH DOSE CHEMOTHERAPY AGENT (MDC 17)
  • MS-DRG 839 — CHEMOTHERAPY WITH ACUTE LEUKEMIA AS SECONDARY DIAGNOSIS WITHOUT CC/MCC (MDC 17)
  • MS-DRG 850 — ACUTE LEUKEMIA WITH OTHER PROCEDURES (MDC 17)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 18 — Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid (supersedes HCC 19, HCC 20, HCC 21, HCC 22, HCC 23)

Other models: CMS-HCC V22 HCC 8 · RxHCC V08 HCC 19

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for C91.00 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on C91.00 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Acute lymphoblastic leukemia with failed remission
  • Acute lymphoblastic leukemia NOS

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from C91

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from C81-C96

Coder workflow for C91.00

MedCoder structured workflow — derived from this code’s own official record

Before you code C91.00

  1. Confirm the documented site and behavior (this code’s block classifies malignant neoplasms), whether the site is primary or secondary, and whether the malignancy is current or a personal history: a previously excised malignancy with no further treatment and no evidence of disease is history, not current disease. Verify the site against the Table of Neoplasms. Neoplasm chapter guidelines (Guidelines I.C.2.a, I.C.2.d, I.C.2.m).

    See the Table of Neoplasms entries · Guide: Active cancer vs history of cancer →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with C91.00. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in C91.00’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewZ85.6

Consider C91.00. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Anatomical site
At the most specific level the record states; a site the classification separates cannot be assumed from a procedure or a measurement.
Acuity
Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).
Remission status
Remission is coded only when the provider documents it.
Behavior and current-versus-history status
Malignant, in situ, benign or uncertain; primary or secondary; current disease or personal history (Guidelines I.C.2.m).

Official instructions as workflow

  • Excludes1 — check before selecting C91.00(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with C91.00: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareZ85.6

    See the official tabular notes · Guidelines I.A.12.a

  • Excludes2 — not part of C91.00(4 notes)

    Coding workflow: The conditions named in this note are not included in C91.00. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareC46.3, C77, C79.52, C78.89

    See the official tabular notes · Guidelines I.A.12.b

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition C91.00 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewZ85.6

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Coding context

The comparisons, hierarchy, index entries, guidelines, relationships, risk-adjustment and coverage context a coder commonly needs. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Don’t confuse C91.00 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of C91.00 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • Z85.6— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of personal history of leukemia moves the case to Z85.6; the two are not reported together unless documented as unrelated.

    Full comparison: C91.00 vs Z85.6 →

  • C46.3— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of Kaposi's sarcoma of lymph nodes adds C46.3; it is not part of this code and both may be reported when both are documented.

    Full comparison: C91.00 vs C46.3 →

  • C77— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of secondary and unspecified neoplasm of lymph nodes adds C77; it is not part of this code and both may be reported when both are documented.

    Full comparison: C91.00 vs C77 →

  • C79.52— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of secondary neoplasm of bone marrow adds C79.52; it is not part of this code and both may be reported when both are documented.

    Full comparison: C91.00 vs C79.52 →

  • C78.89— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of secondary neoplasm of spleen adds C78.89; it is not part of this code and both may be reported when both are documented.

    Full comparison: C91.00 vs C78.89 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Code Overview

Acute lymphoblastic leukemia not having achieved remission is a billable ICD-10-CM diagnosis code (C91.00).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name C91.00 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 5 Excludes1 notes across 4 chapters: C76 — Malignant neoplasm of other and ill-defined sites (via C91.-), D72.8 — Other specified disorders of white blood cells (via C91.-), D72.825 — Bandemia (via C91.-), T66 — Radiation sickness, unspecified (via C91.-), Z85.6 — Personal history of leukemia (via C91.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 4 Code First instructions across 4 chapters: M36.1 — Arthropathy in neoplastic disease (via C91.-), N16 — Renal tubulo-interstitial disorders in diseases classified elsewhere (via C91.-), R50.81 — Fever presenting with conditions classified elsewhere (via C91.-), Z15.0 — Genetic susceptibility to malignant neoplasm (via C91.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 113 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 837-839 (Chemotherapy with Acute Leukemia as Secondary Diagnosis or with High Dose Chemotherapy Agent).

Named in the grouper logic of 10 MS-DRGs: DRG 820 (MDC 17), DRG 821 (MDC 17), DRG 822 (MDC 17), DRG 834 (MDC 17), DRG 835 (MDC 17), DRG 836 (MDC 17), DRG 837 (MDC 17), DRG 838 (MDC 17), DRG 839 (MDC 17), DRG 850 (MDC 17).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):NEO059 — Leukemia - acute lymphoblastic leukemia (ALL) (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

C90.02 — Multiple myeloma in relapse, C90.10 — Plasma cell leukemia not having achieved remission, C90.11 — Plasma cell leukemia in remission, C90.12 — Plasma cell leukemia in relapse, C90.20 — Extramedullary plasmacytoma not having achieved remission, C90.21 — Extramedullary plasmacytoma in remission, C90.22 — Extramedullary plasmacytoma in relapse, C90.30 — Solitary plasmacytoma not having achieved remission, C90.31 — Solitary plasmacytoma in remission, C90.32 — Solitary plasmacytoma in relapse, C91.01 — Acute lymphoblastic leukemia, in remission, C91.02 — Acute lymphoblastic leukemia, in relapse, C91.10 — Chronic lymphocytic leukemia of B-cell type not having achieved remission, C91.11 — Chronic lymphocytic leukemia of B-cell type in remission, C91.12 — Chronic lymphocytic leukemia of B-cell type in relapse, C91.30 — Prolymphocytic leukemia of B-cell type not having achieved remission, C91.31 — Prolymphocytic leukemia of B-cell type, in remission, C91.32 — Prolymphocytic leukemia of B-cell type, in relapse, C91.50 — Adult T-cell lymphoma/leukemia (HTLV-1-associated) not having achieved remission, C91.51 — Adult T-cell lymphoma/leukemia (HTLV-1-associated), in remission, +92 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid) for risk-adjusted payment.

C79.10 — Secondary malignant neoplasm of unspecified urinary organs, C79.11 — Secondary malignant neoplasm of bladder, C79.19 — Secondary malignant neoplasm of other urinary organs, C79.2 — Secondary malignant neoplasm of skin, C79.51 — Secondary malignant neoplasm of bone, C79.52 — Secondary malignant neoplasm of bone marrow, C79.60 — Secondary malignant neoplasm of unspecified ovary, C79.61 — Secondary malignant neoplasm of right ovary, C79.62 — Secondary malignant neoplasm of left ovary, C79.63 — Secondary malignant neoplasm of bilateral ovaries, C79.81 — Secondary malignant neoplasm of breast, C79.82 — Secondary malignant neoplasm of genital organs, C79.89 — Secondary malignant neoplasm of other specified sites, C79.9 — Secondary malignant neoplasm of unspecified site, C80.0 — Disseminated malignant neoplasm, unspecified, C91.01 — Acute lymphoblastic leukemia, in remission, C91.02 — Acute lymphoblastic leukemia, in relapse, C95.00 — Acute leukemia of unspecified cell type not having achieved remission, C95.01 — Acute leukemia of unspecified cell type, in remission, C95.02 — Acute leukemia of unspecified cell type, in relapse, +5 more

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic, Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers, Lung and Other Severe Cancers, Lymphoma and Other Cancers, Bladder, Colorectal, and Other Cancers, Prostate, Breast, and Other Cancers and Tumors

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Leukemia - acute lymphoblastic leukemia (ALL)).

C91.02 — Acute lymphoblastic leukemia, in relapse

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Leukemia, leukemic”, “Burkitt”; these codes share that main term but sit in a different category of the Tabular List.

C83.7 — Burkitt lymphoma (tumor), C83.77 — Burkitt lymphoma, spleen (lymphoma, spleen), C90.1 — Plasma cell leukemia (plasmacytic), C92.0 — Acute myeloblastic leukemia (AML), C92.1 — Chronic myeloid leukemia, BCR/ABL-positive (chronic myelogenous), C92.2 — Atypical chronic myeloid leukemia, BCR/ABL-negative (atypical chronic myeloid, BCR/ABL-negative), C92.4 — Acute promyelocytic leukemia (AML M3), C92.5 — Acute myelomonocytic leukemia (AML M4), C92.6 — Acute myeloid leukemia with 11q23-abnormality (acute myeloid, NOS, with, 11q23-abnormality), C92.9 — Myeloid leukemia, unspecified (myeloid), C92.A — Acute myeloid leukemia with multilineage dysplasia (acute myeloid, NOS, with, multilineage dysplasia), C92.Z — Other myeloid leukemia (myeloid, specified NEC), C93.0 — Acute monoblastic/monocytic leukemia (AML M5), C93.1 — Chronic myelomonocytic leukemia (CMML), C93.3 — Juvenile myelomonocytic leukemia (juvenile myelomonocytic), C93.9 — Monocytic leukemia, unspecified (monocytic), C93.Z — Other monocytic leukemia (monocytic, specified NEC), C94.0 — Acute erythroid leukemia (acute erythroid), C94.2 — Acute megakaryoblastic leukemia (acute megakaryocytic), C94.3 — Mast cell leukemia (mast cell), +5 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Fecal Occult Blood Test (FOBT), Gamma-glutamyl Transferase (GGT) Test, Iron Panel

Contextual Map

Every relationship of C91.00 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run C91.00 with these 9 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Code First instructions

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 18 — Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid [CMS-HCC]: “Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid — supersedes HCC 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers), HCC 20 (Lung and Other Severe Cancers), HCC 21 (Lymphoma and Other Cancers), HCC 22 (Bladder, Colorectal, and Other Cancers), HCC 23 (Prostate, Breast, and Other Cancers and Tumors)”— CMS-HCC V28 · 2026

MS-DRG Grouper (10)

MDC crossing

  • MDC 17 — Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms[MDC crossing]: “Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 4,735 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Nearest codes (36)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Deep reference

Published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 20, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "C91.00 — Acute lymphoblastic leukemia not having achieved remission." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/c91.00-acute-lymphoblastic-leukemia-not-having-achieved-remission

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Acute lymphoblastic leukemia not having achieved remission

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to C91.00 in its code family, with their registry titles.

View all codes in the C91 family