D03.121 ICD-10-CM Code: Melanoma in situ of left upper eyelid, including canthus
D03.121 maps to CMS-HCC V28 23. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Neoplasms (C00-D49) / In situ neoplasms (D00-D09)
D03.121
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMelanoma in situ of left upper eyelid, including canthus
Abnormal melanoma cells on the left upper eyelid or corner of the left eye that have not yet invaded deeper tissue.
Buddy Insight
Melanoma in situ of the left upper eyelid is a non-invasive melanocytic neoplasm confined to the epidermal layer of the left upper eyelid or adjacent left canthal area.
CMS-HCC V28
MappedHCC 23
Coefficient HCC 23: 0.186 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 013
Code-level coefficient reference
ESRD/PACE
MappedHCC 12
Code-level coefficient reference
RXHCC
MappedHCC 22
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for D03.121. Check the code and parent instructions in the Code Book.
Excludes 2
OfficialNo Excludes 2 notes are included in this display for D03.121. Check the code and parent instructions in the Code Book.
Related Codes
Includes
Official- Bowen's diseaseInherited from D00-D09
- erythroplasiaInherited from D00-D09
- grade III intraepithelial neoplasiaInherited from D00-D09
- Queyrat's erythroplasiaInherited from D00-D09
Excludes 1
OfficialNo Excludes 1 notes are included in this display for D03.121. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for D03.121. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for D03.121. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for D03.121. Check the code and parent instructions in the Code Book.
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 D03.121 an HCC code?
Yes. D03.121 (Melanoma in situ of left upper eyelid, including canthus) maps to HCC 23, Prostate, Breast, and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.186. 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: D03.121 is billable and maps to V28 HCC 23, Prostate, Breast, and Other Cancers and Tumors. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- D03.121
- Description
- Melanoma in situ of left upper eyelid, including canthus
- HCC (V28)
- HCC 23 — Prostate, Breast, and Other Cancers and Tumors
- RAF reference coefficient
- 0.186
- 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 D03.121 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for D03.121
For D03.121, 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.
- 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
Coder workflow notes
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What This Code Means
D03.121 is the ICD-10-CM diagnosis code for melanoma in situ of left upper eyelid, including canthus. Abnormal melanoma cells on the left upper eyelid or corner of the left eye that have not yet invaded deeper tissue. D03.121 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, D03.121 maps to Prostate, Breast, and Other Cancers and Tumors (HCC 23) with a source-labeled community, non-dual, aged reference coefficient of 0.186. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. 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.
This code specifies the left upper eyelid - confirm documentation indicates left side and upper eyelid location. For D03.121, 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. 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 D03.121 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code specifies the left upper eyelid - confirm documentation indicates left side and upper eyelid location
- •Distinguish from D03.122 which codes the left lower eyelid
Clinical Significance
Melanoma in situ of the left upper eyelid is a non-invasive melanocytic neoplasm confined to the epidermal layer of the left upper eyelid or adjacent left canthal area. Upper eyelid melanoma in situ can be particularly challenging to detect due to partial concealment by the brow and eyelid fold. Early biopsy of any new or changing pigmented lesion in this area is critical for timely diagnosis.
Documentation Requirements
- ✓Pathology must confirm melanoma in situ with no dermal invasion.
- ✓Left laterality and upper eyelid location must be explicitly documented.
- ✓Include the dimensions of the lesion, dermoscopic findings, and whether the medial or lateral canthus is involved for comprehensive clinical documentation.