D03.21
BillableMelanoma in situ of right ear and external auricular canal
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D03.21 an HCC code?
Yes. D03.21 maps to Melanoma and Other Skin Cancers under the CMS-HCC V28 risk adjustment model (and Breast, Prostate, and Other Cancers and Tumors 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 D03.21
For D03.21 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 D03.21 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D03.21 is the ICD-10-CM diagnosis code for melanoma in situ of right ear and external auricular canal. Abnormal melanoma cells on the right ear or in the right ear canal that have not yet invaded deeper tissue. D03.21 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering in situ neoplasms (d00-d09).
Under the CMS-HCC V28 risk adjustment model, D03.21 maps to Melanoma and Other Skin Cancers (HCC 23) with a community, non-dual, aged base RAF weight of 0.251. Under the older CMS-HCC V24 model, D03.21 maps to Breast, Prostate, and Other Cancers and Tumors (HCC 12) with a community, non-dual, aged base RAF weight of 0.150. 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.
This code specifies the right ear - ensure documentation clearly indicates right-sided involvement. Because D03.21 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 D03.21 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code specifies the right ear - ensure documentation clearly indicates right-sided involvement
- •Includes both the auricle (external ear) and the external auditory canal
Clinical Significance
Melanoma in situ of the right ear and external auricular canal is a non-invasive melanocytic neoplasm confined to the epidermis of the right ear. The ear's convex surface with chronic ultraviolet exposure makes it a common site for cutaneous melanoma development. Complete excision with margin assessment is the standard treatment, with particular attention to the complex contours of the auricular cartilage.
Documentation Requirements
- ✓Biopsy confirmation with pathology documenting epidermal confinement and right-sided laterality.
- ✓Specify the exact location on the ear (helix, antihelix, lobule, concha, external canal) and document surgical margins, any reconstructive approach, and surveillance plan.