Question 1

What is ICD-10 code M86.442?

Accepted Answer

M86.442 is the ICD-10-CM diagnosis code for Chronic osteomyelitis with draining sinus, left hand. A long-term bone infection in the left hand with an open drainage tract that allows infected material to drain through the skin. M86.442 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M86.442 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Question 2

Is M86.442 an HCC code?

Accepted Answer

Yes. The final FY2026 CMS mapping file maps M86.442 to HCC 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis) under CMS-HCC V28 with source-labeled reference coefficients HCC 92 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.

Question 3

Is M86.442 billable?

Accepted Answer

Yes. M86.442 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. M86.442 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

Which HCC does M86.442 map to under V28?

Accepted Answer

M86.442 maps to CMS-HCC V28 HCC 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis).  The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

Question 5

What RAF reference is published for M86.442?

Accepted Answer

M86.442 has source-labeled community, non-dual, aged reference coefficients HCC 92 0.479 under CMS-HCC V28 for payment year 2026.  The coefficients come from the CMS V28 relative-factor file. 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.

Question 6

What is the V28 vs V24 difference for M86.442?

Accepted Answer

For M86.442, the current CMS-HCC V28 result is HCC 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis). Select a historical effective period before comparing a V24 mapping.  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.

Question 7

What documentation supports M86.442?

Accepted Answer

Verify left hand is documented in the clinical record; use M86.441 for right hand involvement Document the presence of draining sinus to support this specific code selection For M86.442, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. One mnemonic element does not establish that a diagnosis is reportable.

Question 8

Can M86.442 be a primary diagnosis?

Accepted Answer

Yes. M86.442 carries no code-first instruction in the FY2026 tabular, so it can be the first-listed diagnosis when it is the condition chiefly responsible for the encounter and the note supports it, and it can also be reported as a secondary diagnosis. For risk adjustment the order does not matter; the V28 category is the same either way.

Question 9

Which codes cannot be reported with M86.442?

Accepted Answer

The Excludes1 note that applies to M86.442 lists postprocedural osteopathies (M96.-); osteomyelitis due to: echinococcus (B67.2); gonococcus (A54.43); salmonella (A02.24). An Excludes1 condition is not reported together with M86.442; report one or the other, unless the two conditions are unrelated, which the ICD-10-CM Official Guidelines (Section I.A.12.a) allow. The Excludes2 note lists arthropathic psoriasis (L40.5-); certain conditions originating in the perinatal period (P04-P96); certain infectious and parasitic diseases (A00-B99); compartment syndrome (traumatic) (T79.A-); and 9 more (see the notes on this page); those are separate conditions that may be reported together with M86.442 when both are documented.

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M86.442 ICD-10-CM Code: Chronic osteomyelitis with draining sinus, left hand

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M86.442

Is M86.442 an HCC code?

HCC Category Mapping

MEAT review for M86.442

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What This Code Means

Coding Tips

Clinical Significance

Documentation Requirements

Commonly Confused Codes

Child Codes

Code Hierarchy

Also searched as

Work M86.442 in HCC Buddy