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C88.91 ICD-10-CM Code: Malignant immunoproliferative disease, unspecified, in remission

C88.91 maps to CMS-HCC V28 21. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

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Code lookupC88.91

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lymphoid, hematopoietic and related tissue (C81-C96)

C88.91

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant immunoproliferative disease, unspecified, in remission

A cancer of immune cells of an unspecified type that is currently in remission.

Buddy the Bee presenting code insight

Buddy Insight

Malignant immunoproliferative disease, unspecified, in remission indicates a malignant immunoproliferative process of undetermined type that has responded to treatment.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 21

Coefficient HCC 21: 0.671 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 010

Code-level coefficient reference

ESRD/PACE

HCC 10

Code-level coefficient reference

RXHCC

HCC 21

Code-level coefficient reference

Code Book Path

Official
C88Malignant immunoproliferative diseases and certain other B-cell lymphomasC88.9Malignant immunoproliferative disease, unspecifiedC88.91Malignant immunoproliferative disease, unspecified, in remission

Inclusion Terms

Official
  • Immunoproliferative disease NOSInherited from C88.9

Excludes 2

Official
  • Kaposi's sarcoma of lymph nodes (C46.3)Inherited from C81-C96
  • secondary and unspecified neoplasm of lymph nodes (C77.-)Inherited from C81-C96
  • secondary neoplasm of bone marrow (C79.52)Inherited from C81-C96
  • secondary neoplasm of spleen (C78.89)Inherited from C81-C96

Related Codes

Official
C88.90Malignant immunoproliferative disease, unspecified not having achieved remission

Includes

Official

No Includes notes are included in this display for C88.91. Check the code and parent instructions in the Code Book.

Excludes 1

Official
  • B-cell lymphoma, unspecified (C85.1-)Inherited from C88
  • personal history of other malignant neoplasms of lymphoid, hematopoietic and related tissues (Z85.79)Inherited from C88

Code First

Official

No Code First sequencing instructions are included in this display for C88.91. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C88.91. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C88.91. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Remission must be explicitly documented by the provider.
Available clinical and laboratory data supporting the original malignant immunoproliferative diagnosis should be in the record.
The reason for lack of specificity in the diagnosis should be documented.
Surveillance plan and monitoring schedule must be recorded.

MEAT Support

HCC Buddy guidance
Remission must be explicitly documented by the provider.
Available clinical and laboratory data supporting the original malignant immunoproliferative diagnosis should be in the record.
The reason for lack of specificity in the diagnosis should be documented.
Surveillance plan and monitoring schedule must be recorded.

Audit Caution

HCC Buddy guidance
This doubly unspecified code (unspecified type plus remission) should prompt review of the medical record to determine if a more specific code can be assigned.
Do not assume remission without explicit documentation.
Continue using this as an active malignancy code during surveillance rather than switching to a history code.

Common Mistakes

HCC Buddy guidance
C88.90 (malignant immunoproliferative disease, unspecified, not in remission) indicates active disease.
C88.81 (other malignant immunoproliferative diseases in remission) provides slightly more specificity.
Z85.79 (personal history of malignant neoplasm of lymphoid tissue) is for definitively cured disease only.

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C88.91 an HCC code?

Yes. C88.91 (Malignant immunoproliferative disease, unspecified, in remission) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C88.91 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
C88.91
Description
Malignant immunoproliferative disease, unspecified, in remission
HCC (V28)
HCC 21 — Lymphoma and Other Cancers
RAF reference coefficient
0.671
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers
0.671
ESRDHCC 10, Lymphoma and Other Cancers
Not separately weighted
RxHCCHCC 21, Lymphomas and Other Hematologic Cancers
Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C88.91 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C88.91

For C88.91, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

  • MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
  • EEvaluate: test results, medication response, or physical findings reviewed by the provider
  • AAssess: explicit mention in the assessment or plan with acknowledgment of status
  • TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

C88.91 is the ICD-10-CM diagnosis code for malignant immunoproliferative disease, unspecified, in remission. A cancer of immune cells of an unspecified type that is currently in remission. C88.91 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of lymphoid, hematopoietic and related tissue (c81-c96).

Under the CMS-HCC V28 risk adjustment model, C88.91 maps to Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. No V24 mapping is shown for C88.91; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Verify documentation explicitly states remission status before assigning the fifth character '1'. For C88.91, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for C88.91 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Verify documentation explicitly states remission status before assigning the fifth character '1'
  • •If the specific immunoproliferative disease type can be identified, use a more specific code instead

Clinical Significance

Malignant immunoproliferative disease, unspecified, in remission indicates a malignant immunoproliferative process of undetermined type that has responded to treatment. The unspecified nature of this code suggests insufficient diagnostic workup or documentation to classify the specific disease entity. Despite the lack of diagnostic precision, the remission status reflects a favorable treatment response.

Documentation Requirements

  • ✓Remission must be explicitly documented by the provider.
  • ✓Available clinical and laboratory data supporting the original malignant immunoproliferative diagnosis should be in the record.
  • ✓The reason for lack of specificity in the diagnosis should be documented.
  • ✓Surveillance plan and monitoring schedule must be recorded.

Commonly Confused Codes

  • •C88.90 (malignant immunoproliferative disease, unspecified, not in remission) indicates active disease.
  • •C88.81 (other malignant immunoproliferative diseases in remission) provides slightly more specificity.
  • •Z85.79 (personal history of malignant neoplasm of lymphoid tissue) is for definitively cured disease only.

Child Codes

C88.90Malignant immunoproliferative disease, unspecified not having achieved remission
HCC 21
C88.91Malignant immunoproliferative disease, unspecified, in remission
HCC 21

Code Hierarchy

└C88Malignant immunoproliferative diseases and certain other B-cell lymphomas└C88.9Malignant immunoproliferative disease, unspecified└C88.91Malignant immunoproliferative disease, unspecified, in remission
└C88.91Malignant immunoproliferative disease, unspecified, in remission

C88.91 code history

Code setChange
FY2025 (effective Oct 1, 2024)Added to the code set

Source: official CMS ICD-10-CM order and addenda files, FY2016 through FY2027.

Also searched as

  • C88 91
  • C8891

For C88.91, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

C88.91 maps to CMS-HCC V28 category 21, Lymphoma and Other Cancers. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for C88.91. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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