M86.322
BillableChronic multifocal osteomyelitis, left humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.322 an HCC code?
Yes. M86.322 maps to Bone/Joint/Muscle Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis 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 M86.322
For M86.322 to 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 M86.322 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.322 is the ICD-10-CM diagnosis code for chronic multifocal osteomyelitis, left humerus. A long-standing bone infection affecting multiple bones, specifically involving the left upper arm bone (humerus). M86.322 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
Under the CMS-HCC V28 risk adjustment model, M86.322 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.209. Under the older V24 model, M86.322 mapped to the same category but with a base RAF weight of 0.482 — 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.
This code indicates the left humerus is one of multiple affected sites; document all other involved locations. Because M86.322 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 M86.322 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code indicates the left humerus is one of multiple affected sites; document all other involved locations.
- •Confirm laterality is documented as 'left' in the clinical documentation.
Clinical Significance
Chronic multifocal osteomyelitis of the left humerus indicates a complex, persistent bone infection that significantly compromises upper extremity function and requires comprehensive medical management. The multifocal pattern suggests widespread skeletal involvement, necessitating aggressive treatment approaches and continuous monitoring for progression and complications.
Documentation Requirements
- ✓Documented diagnosis of chronic osteomyelitis
- ✓Evidence of multifocal bone involvement beyond single site
- ✓Specific anatomic identification of left humerus
- ✓Laboratory evidence of infection (ESR, CRP, cultures)
- ✓Imaging studies demonstrating osteomyelitis changes
- ✓Comprehensive treatment history and current therapy
- ✓Documentation of any surgical interventions
- ✓Assessment of functional limitations and prognosis