What is ICD-10 code C46.0?

C46.0 is the ICD-10-CM diagnosis code for Kaposi's sarcoma of skin. A cancer of blood vessel cells in the skin that appears as purple or dark lesions, commonly seen in patients with weakened immune systems. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C46.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C46.0 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.

Yes. C46.0 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. C46.0 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.

What is the V28 vs V24 difference for C46.0?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For C46.0, V28 maps to Lymphoma and Other Cancers at RAF 0.671 while V24 mapped to Lymphoma and Other Cancers at RAF 0.675. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting C46.0?

Kaposi's sarcoma of skin is often associated with HIV/AIDS; document immunocompromised status and CD4 count if available Specify the anatomical site of skin involvement (face, extremities, etc.) in addition to this code for complete documentation Because C46.0 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

2026 ICD-10-CM C46.0: Kaposi's sarcoma of skin

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupC46.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of mesothelial and soft tissue (C45-C49)

C46.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Kaposi's sarcoma of skin

A cancer of blood vessel cells in the skin that appears as purple or dark lesions, commonly seen in patients with weakened immune systems.

Buddy Insight

CMS-HCC V28

Mapped

HCC 21

Lymphoma and Other Cancers

RAF 0.671

CMS-HCC V24

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.675

ACA/HHS

Mapped

HCC 10

HHS-HCC 10

Varies by metal level

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

RAF 0.111

RXHCC

Mapped

HCC 20

Cancer, Liver and Intrahepati...

RAF 0.491

Code Book Path

Official

C46Kaposi's sarcoma

C46.0Kaposi's sarcoma of skin

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C46.0 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C46.0 in this effective period.

Related Child Codes

Official

C46.1Kaposi's sarcoma of soft tissue

C46.2Kaposi's sarcoma of palate

C46.3Kaposi's sarcoma of lymph nodes

C46.4Kaposi's sarcoma of gastrointestinal sites

C46.5Kaposi's sarcoma of lung

Includes

Official

ICD-10-CM does not list Includes notes for C46.0 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C46.0 in this effective period.

Code First

Official

any human immunodeficiency virus [HIV] disease (B20)

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C46.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C46.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology-confirmed diagnosis of Kaposi sarcoma (not just clinical suspicion)

Underlying immunodeficiency status (Human Immunodeficiency Virus infection, transplant-related immunosuppression, or other)

Number, size, and distribution of cutaneous lesions

Current treatment (antiretroviral therapy, chemotherapy, radiation, or observation)

MEAT Support

HCC Buddy guidance

Pathology-confirmed diagnosis of Kaposi sarcoma (not just clinical suspicion)

Underlying immunodeficiency status (Human Immunodeficiency Virus infection, transplant-related immunosuppression, or other)

Number, size, and distribution of cutaneous lesions

Current treatment (antiretroviral therapy, chemotherapy, radiation, or observation)

Audit Caution

HCC Buddy guidance

Failing to code the underlying Human Immunodeficiency Virus disease (B20) as an additional diagnosis when applicable

Coding resolved Kaposi sarcoma as active — only code if current/active disease documented in the encounter

Confusing Kaposi sarcoma with bacillary angiomatosis (A44.1), which can mimic it clinically in immunocompromised patients

Not querying whether lesions represent skin-only involvement versus deeper soft tissue extension

Common Mistakes

HCC Buddy guidance

C46.1 (Kaposi sarcoma of soft tissue) — use when deeper soft tissue structures are involved, not just skin surface

C46.9 (Kaposi sarcoma, unspecified) — avoid when skin involvement is documented; use C46.0 instead

D18.01 (Hemangioma of skin and subcutaneous tissue) — benign vascular lesion, not malignant Kaposi sarcoma

C44._ (Other malignant neoplasm of skin) — different skin cancer types such as squamous cell or basal cell carcinoma

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 C46.0 an HCC code?

Yes. C46.0 (Kaposi's sarcoma of skin) maps to Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24), with a community non-dual aged RAF of 0.671. It is billable for payment year 2026.

Coder answer: C46.0 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C46.0
Description: Kaposi's sarcoma of skin
HCC (V28): HCC 21 — Lymphoma and Other Cancers
RAF: 0.671
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers

0.671

V24HCC 10, Lymphoma and Other Cancers

0.675

ESRDHCC 10, Lymphoma and Other Cancers

0.111

RxHCCHCC 20, Cancer, Liver and Intrahepatic Bile Duct

0.491

Each model's RAF is its CMS base weight for that model's standard population, so 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 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.

Work C46.0 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C46.0

For C46.0 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 C46.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C46.0 is the ICD-10-CM diagnosis code for kaposi's sarcoma of skin. A cancer of blood vessel cells in the skin that appears as purple or dark lesions, commonly seen in patients with weakened immune systems. C46.0 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of mesothelial and soft tissue (c45-c49).

Under the CMS-HCC V28 risk adjustment model, C46.0 maps to Lymphoma and Other Cancers (HCC 21) with a community, non-dual, aged base RAF weight of 0.671. Under the older V24 model, C46.0 mapped to the same category but with a base RAF weight of 0.675, V28 recalibrated weights across the entire model. 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.

Kaposi's sarcoma of skin is often associated with HIV/AIDS; document immunocompromised status and CD4 count if available. Because C46.0 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 C46.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Kaposi's sarcoma of skin is often associated with HIV/AIDS; document immunocompromised status and CD4 count if available
•Specify the anatomical site of skin involvement (face, extremities, etc.) in addition to this code for complete documentation

Clinical Significance

Kaposi sarcoma of the skin is a vascular malignancy most commonly associated with Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome but can also occur in immunosuppressed transplant patients or as classic/endemic forms. Skin involvement is the most common presentation and its capture is important for reflecting the patient's immunocompromised status and ongoing oncologic care needs.

Documentation Requirements

✓Pathology-confirmed diagnosis of Kaposi sarcoma (not just clinical suspicion)
✓Underlying immunodeficiency status (Human Immunodeficiency Virus infection, transplant-related immunosuppression, or other)
✓Number, size, and distribution of cutaneous lesions
✓Current treatment (antiretroviral therapy, chemotherapy, radiation, or observation)
✓CD4 count and viral load if Human Immunodeficiency Virus-associated

Commonly Confused Codes

•C46.1 (Kaposi sarcoma of soft tissue): use when deeper soft tissue structures are involved, not just skin surface
•C46.9 (Kaposi sarcoma, unspecified): avoid when skin involvement is documented; use C46.0 instead
•D18.01 (Hemangioma of skin and subcutaneous tissue): benign vascular lesion, not malignant Kaposi sarcoma
•C44._ (Other malignant neoplasm of skin): different skin cancer types such as squamous cell or basal cell carcinoma