HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
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 guidanceMalignant immunoproliferative disease, unspecified, in remission
A cancer of immune cells of an unspecified type that is currently in remission.
Buddy Insight
Malignant immunoproliferative disease, unspecified, in remission indicates a malignant immunoproliferative process of undetermined type that has responded to treatment.
CMS-HCC V28
MappedHCC 21
RAF 0.545
CMS-HCC V24
MappedHCC 10
RAF 0.675
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 10
RAF 0.0
RXHCC
MappedHCC 21
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
Official- Immunoproliferative disease NOS
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for C88.91 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for C88.91 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for C88.91 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C88.91 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for C88.91 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for C88.91 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is C88.91 an HCC code?
Yes. C88.91 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for C88.91
For C88.91to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C88.91 during that encounter — not just copy-forwarded from a problem list.
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 Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C88.91 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Verify documentation explicitly states remission status before assigning the fifth character '1'. Because C88.91 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, 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.