M86.521 ICD-10-CM Code: Other chronic hematogenous osteomyelitis, right humerus
M86.521 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)
M86.521
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther chronic hematogenous osteomyelitis, right humerus
A chronic bone infection of the right upper arm bone (humerus) that originated from a bloodstream infection.
Buddy Insight
Other chronic hematogenous osteomyelitis of the right humerus represents a blood-borne bone infection that has become chronic, specifically affecting the right upper arm bone.
CMS-HCC V28
MappedHCC 92
Code-level coefficient reference
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 055
Code-level coefficient reference
ESRD/PACE
MappedHCC 39
Code-level coefficient reference
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M86.521 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M86.521 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M86.521 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M86.521 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M86.521 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M86.521 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M86.521 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is M86.521 an HCC code?
Yes. M86.521 (Other chronic hematogenous osteomyelitis, right humerus) maps to HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.479. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: M86.521 is billable and maps to V28 HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- M86.521
- Description
- Other chronic hematogenous osteomyelitis, right humerus
- HCC (V28)
- HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
- RAF reference coefficient
- 0.479
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work M86.521 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT Criteria for M86.521
For M86.521 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 M86.521 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
M86.521 is the ICD-10-CM diagnosis code for other chronic hematogenous osteomyelitis, right humerus. A chronic bone infection of the right upper arm bone (humerus) that originated from a bloodstream infection. M86.521 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, M86.521 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a source-labeled community, non-dual, aged reference coefficient of 0.479. No V24 mapping is shown for M86.521; use the applicable model and payment year when reviewing the V28 mapping. 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. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
The humerus is the long bone of the upper arm; ensure this is the documented site and not the shoulder joint. Because M86.521 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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, source-labeled coefficient references, and MEAT documentation criteria for M86.521 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The humerus is the long bone of the upper arm; ensure this is the documented site and not the shoulder joint
- •Use M86.522 for left humerus infections
Clinical Significance
Other chronic hematogenous osteomyelitis of the right humerus represents a blood-borne bone infection that has become chronic, specifically affecting the right upper arm bone. This condition indicates systemic infection with targeted skeletal involvement requiring prolonged IV antibiotic therapy and monitoring, significantly impacting upper extremity function and overall patient health status.
Documentation Requirements
- ✓Documentation of chronic osteomyelitis diagnosis
- ✓Clear evidence of hematogenous (blood-borne) origin
- ✓Specific anatomic identification of right humerus involvement
- ✓Laboratory studies confirming systemic infection
- ✓Blood culture results or evidence of bacteremia
- ✓Treatment history including IV antibiotic duration
- ✓Imaging studies demonstrating right humerus infection
- ✓Assessment of upper extremity function and treatment response
Commonly Confused Codes
- •M86.522: Other chronic hematogenous osteomyelitis, left humerus (wrong laterality)
- •M86.621: Other chronic osteomyelitis, right humerus (not specifically hematogenous)
- •M86.321: Chronic multifocal osteomyelitis, right humerus (multifocal rather than hematogenous)
- •M86.421: Chronic osteomyelitis with draining sinus, right humerus (has draining component)