M86.38
BillableChronic multifocal osteomyelitis, other site
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.38 an HCC code?
Yes. M86.38 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 M86.38
For M86.38 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 M86.38 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.38 is the ICD-10-CM diagnosis code for chronic multifocal osteomyelitis, other site. A chronic bone infection affecting multiple areas in locations other than the common sites like shoulder, arm, hip, leg, ankle, or foot. M86.38 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, M86.38 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, M86.38 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.
Document the specific anatomical site affected in the medical record. Because M86.38 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 M86.38 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
- •Use this code for multifocal osteomyelitis of the spine, pelvis, or other unusual locations
Clinical Significance
Chronic multifocal osteomyelitis at other sites represents a severe bone infection affecting locations not commonly specified, indicating complex disease requiring specialized management. This diagnosis captures multifocal infections in areas such as spine, pelvis, or skull that may have unique treatment challenges.
Documentation Requirements
- ✓Documentation of specific anatomical site not covered by common locations
- ✓Evidence of chronicity (>6 weeks duration or recurrent episodes)
- ✓Confirmation of multifocal involvement at the specified site
- ✓Radiographic findings demonstrating chronic osteomyelitic changes
- ✓Clinical symptoms related to the affected anatomical area
- ✓Laboratory evidence supporting chronic infectious process
- ✓Treatment documentation specific to the unusual location
- ✓Provider assessment confirming chronic multifocal osteomyelitis
Commonly Confused Codes
- •M86.30 — Chronic multifocal osteomyelitis, unspecified site when site is known
- •M86.68 — Other chronic osteomyelitis, other site, lacks multifocal component
- •M86.18 — Acute osteomyelitis, other site, differs by chronicity
- •M86.48 — Chronic osteomyelitis with draining sinus, other site
- •M86.58 — Other chronic hematogenous osteomyelitis, other site