M86.342
BillableChronic multifocal osteomyelitis, left hand
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.342 an HCC code?
Yes. M86.342 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 M86.342
For M86.342 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 M86.342 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.342 is the ICD-10-CM diagnosis code for chronic multifocal osteomyelitis, left hand. A chronic bone infection affecting multiple areas of the bones in the left hand, including the metacarpals and phalanges. M86.342 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, M86.342 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, M86.342 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.
Verify left hand involvement is explicitly documented in the clinical notes. Because M86.342 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 M86.342 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify left hand involvement is explicitly documented in the clinical notes
- •Ensure multifocal involvement is confirmed before coding
Clinical Significance
This code captures chronic multifocal osteomyelitis specifically affecting the left hand, a condition that significantly impacts fine motor function and activities of daily living. The multifocal nature indicates extensive disease requiring comprehensive treatment and rehabilitation.
Documentation Requirements
- ✓Clear documentation of left hand bone involvement
- ✓Evidence supporting chronic nature (>6 weeks or recurrent)
- ✓Confirmation of multifocal pattern in hand bones
- ✓Radiographic evidence of chronic osteomyelitic changes
- ✓Functional assessment of left hand capabilities
- ✓Laboratory markers consistent with chronic infection
- ✓Treatment history including antibiotics and surgical interventions
- ✓Clinical correlation with chronic multifocal osteomyelitis diagnosis