C46.52 maps to CMS-HCC V28 21. 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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Code lookupC46.52

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C46.52

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

Kaposi's sarcoma of left lung

A type of cancer called Kaposi's sarcoma that develops specifically in the left lung.

Buddy Insight

Kaposi sarcoma of the left lung is the laterality-specific code for left-sided pulmonary involvement.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 21

Lymphoma and Other Cancers

Coefficient HCC 21: 0.671 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 010

HHS-HCC 010 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 10

Lymphoma and Other Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 20

Lung, Kidney, and Other Cance...

Code-level coefficient reference

Code Book Path

Official

C46Kaposi's sarcoma C46.5Kaposi's sarcoma of lung C46.52Kaposi's sarcoma of left lung

Inclusion Terms

Official

No inclusion terms are included in this display for C46.52. Check the code and parent instructions in the Code Book.

Excludes 2

Official

No Excludes 2 notes are included in this display for C46.52. Check the code and parent instructions in the Code Book.

Related Codes

Official

C46.50Kaposi's sarcoma of unspecified lung C46.51Kaposi's sarcoma of right lung

Includes

Official

No Includes notes are included in this display for C46.52. Check the code and parent instructions in the Code Book.

Excludes 1

Official

No Excludes 1 notes are included in this display for C46.52. Check the code and parent instructions in the Code Book.

Code First

Official

any human immunodeficiency virus [HIV] disease (B20)Inherited from C46

Use Additional

Official

No Use Additional Code instructions are included in this display for C46.52. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C46.52. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Imaging confirming left lung involvement specifically

Pathology or cytology confirming Kaposi sarcoma

Extent of left lung involvement and any pleural effusion

Current treatment including systemic therapy and respiratory support

MEAT Support

HCC Buddy guidance

Imaging confirming left lung involvement specifically

Pathology or cytology confirming Kaposi sarcoma

Extent of left lung involvement and any pleural effusion

Current treatment including systemic therapy and respiratory support

Audit Caution

HCC Buddy guidance

Using the unspecified code C46.50 when left-sided involvement is clearly documented

Confusing Kaposi sarcoma with primary bronchogenic carcinoma on imaging alone

Not coding both C46.51 and C46.52 when bilateral pulmonary involvement is present

Failing to capture the underlying immunodeficiency with an additional code

Common Mistakes

HCC Buddy guidance

C46.50 (Kaposi sarcoma of unspecified lung) — only when laterality is unknown

C46.51 (Kaposi sarcoma of right lung) — opposite laterality

C34.12 (Malignant neoplasm of upper lobe, left bronchus or lung) — primary lung cancer

C78.02 (Secondary malignant neoplasm of left lung) — metastatic disease to left lung

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 C46.52 an HCC code?

Yes. C46.52 (Kaposi's sarcoma of left lung) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. 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: C46.52 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: C46.52
Description: Kaposi's sarcoma of left lung
HCC (V28): HCC 21 — Lymphoma and Other Cancers
RAF reference coefficient: 0.671
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers

0.671

ESRDHCC 10, Lymphoma and Other Cancers

Not separately weighted

RxHCCHCC 20, Lung, Kidney, and Other Cancers; Secondary Cancer of Lymph Nodes and Other Sites

Not separately weighted

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 C46.52 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C46.52

For C46.52, 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

C46.52 is the ICD-10-CM diagnosis code for kaposi's sarcoma of left lung. A type of cancer called Kaposi's sarcoma that develops specifically in the left lung. C46.52 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, C46.52 maps to Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. 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 requires documentation of left lung involvement; verify laterality is explicitly documented. For C46.52, 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 C46.52 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code requires documentation of left lung involvement; verify laterality is explicitly documented.
•Consider coding concurrent pulmonary complications or respiratory symptoms separately.

Clinical Significance

Kaposi sarcoma of the left lung is the laterality-specific code for left-sided pulmonary involvement. Coding to this level of specificity demonstrates documentation quality and supports accurate disease surveillance in immunocompromised patients.

Documentation Requirements

✓Imaging confirming left lung involvement specifically
✓Pathology or cytology confirming Kaposi sarcoma
✓Extent of left lung involvement and any pleural effusion
✓Current treatment including systemic therapy and respiratory support
✓Immunodeficiency status documentation

Commonly Confused Codes

•C46.50 (Kaposi sarcoma of unspecified lung): only when laterality is unknown
•C46.51 (Kaposi sarcoma of right lung): opposite laterality
•C34.12 (Malignant neoplasm of upper lobe, left bronchus or lung): primary lung cancer
•C78.02 (Secondary malignant neoplasm of left lung): metastatic disease to left lung