T87.42
BillableInfection of amputation stump, left upper extremity
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is T87.42 an HCC code?
Yes. T87.42 maps to Amputation Status, Lower Limb/Amputation Complications under the CMS-HCC V28 risk adjustment model (and Amputation Status, Lower Limb/Amputation Complications 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 T87.42
For T87.42 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 T87.42 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
T87.42 is the ICD-10-CM diagnosis code for infection of amputation stump, left upper extremity. A bacterial or fungal infection occurring at the site of a left arm amputation. T87.42 sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering complications of surgical and medical care, not elsewhere classified (t80-t88).
Under the CMS-HCC V28 risk adjustment model, T87.42 maps to Amputation Status, Lower Limb/Amputation Complications (HCC 409) with a community, non-dual, aged base RAF weight of 0.350. The V24 model used during the PY2024–PY2025 transition mapped T87.42 the same way and at the same RAF weight. 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 laterality in the medical record to ensure correct code selection. Because T87.42 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 T87.42 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify laterality in the medical record to ensure correct code selection
- •Document infection severity and any systemic complications
Clinical Significance
Left upper extremity amputation stump infection represents a critical complication that can jeopardize prosthetic rehabilitation and functional recovery. These infections require prompt intervention to prevent progression to osteomyelitis or systemic sepsis.
Documentation Requirements
- ✓Specific documentation of left upper extremity amputation stump
- ✓Clinical findings consistent with active infection
- ✓Wound assessment including appearance and drainage
- ✓Microbiological studies including culture and sensitivity
- ✓Documentation of systemic signs if present
- ✓Current antibiotic regimen and response to treatment
- ✓Assessment of impact on prosthetic fitting or therapy
- ✓Comorbid conditions affecting healing
Commonly Confused Codes
- •T87.41 — Right upper extremity infection vs left upper extremity
- •T87.40 — Unspecified extremity when laterality is documented
- •T87.43-T87.44 — Lower extremity infections vs upper extremity location
- •L03.115 — Cellulitis of left upper limb (non-amputation specific)
- •T87.32 — Neuroma of left upper extremity vs infectious complication