M08.88 ICD-10-CM Code: Other juvenile arthritis, other specified site
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 / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Inflammatory polyarthropathies (M05-M14)
M08.88
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther juvenile arthritis, other specified site
A type of arthritis that develops in children affecting joints or body areas not specifically listed in other juvenile arthritis codes, such as the spine, pelvis, or other less common sites.
Buddy Insight
Other juvenile arthritis at other specified sites represents chronic inflammatory disease affecting joints not commonly categorized, requiring specialized pediatric rheumatology management.
CMS-HCC V28
MappedHCC 93
RAF 0.175
CMS-HCC V24
MappedHCC 40
RAF 0.307
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 40
RAF 0.0
RXHCC
MappedHCC 83
RAF 0.0
Code Trumping
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Code Book Path
Inclusion Terms
Official- Other juvenile arthritis, vertebrae
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M08.88 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M08.88 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M08.88 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M08.88 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M08.88 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M08.88 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 M08.88 an HCC code?
Yes. M08.88 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease 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 M08.88
For M08.88to 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 M08.88 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
M08.88 is the ICD-10-CM diagnosis code for other juvenile arthritis, other specified site. A type of arthritis that develops in children affecting joints or body areas not specifically listed in other juvenile arthritis codes, such as the spine, pelvis, or other less common sites. M08.88 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).
Under the CMS-HCC V28 risk adjustment model, M08.88 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 93) with a community, non-dual, aged base RAF weight of 0.175. Under the older V24 model, M08.88 mapped to the same category but with a base RAF weight of 0.307, V28 recalibrated weights across the entire model. 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.
Document the specific anatomical site affected in the medical record to support this code selection. Because M08.88 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 M08.88 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document the specific anatomical site affected in the medical record to support this code selection
- •Use this code when the site is documented but does not fit into the standard joint categories (shoulder, elbow, wrist, hip, knee, ankle, foot)
Clinical Significance
Other juvenile arthritis at other specified sites represents chronic inflammatory disease affecting joints not commonly categorized, requiring specialized pediatric rheumatology management. This diagnosis indicates need for individualized treatment approaches, ongoing monitoring, and assessment for systemic complications in pediatric patients.
Documentation Requirements
- ✓Patient age at onset documented as under 16 years
- ✓Evidence of juvenile arthritis at specific anatomic site not elsewhere classified
- ✓Clear documentation of the specific joint or body region affected
- ✓Confirmation of 'other' type of juvenile arthritis (not rheumatoid or unspecified)
- ✓Physical examination findings of joint inflammation at specified site
- ✓Laboratory studies supporting inflammatory arthritis diagnosis
- ✓Treatment plan appropriate for juvenile inflammatory arthritis
- ✓Assessment of functional impact related to specific site involvement
Commonly Confused Codes
- •M08.0: Unspecified juvenile rheumatoid arthritis versus other juvenile arthritis
- •M08.90: Juvenile arthritis unspecified versus other specified type
- •M08.2: Juvenile rheumatoid arthritis with systemic onset when systemic features present
- •M25.9: Joint disorder unspecified versus confirmed juvenile arthritis
- •M06.9: Adult rheumatoid arthritis versus juvenile onset