What is ICD-10 code C49.4?

C49.4 is the ICD-10-CM diagnosis code for Malignant neoplasm of connective and soft tissue of abdomen. A malignant (cancerous) tumor that develops in the soft tissues or connective tissues of the abdominal wall or cavity, such as muscles, fat, or fibrous tissue. C49.4 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C49.4 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. C49.4 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. C49.4 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.

Which HCC does C49.4 map to under V28?

C49.4 maps to CMS-HCC V28 23 (Prostate, Breast, and Other Cancers and Tumors). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does C49.4 pay in RAF?

C49.4 carries a community, non-dual, aged (CNA) RAF weight of 0.186 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for C49.4?

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 C49.4, V28 maps to Prostate, Breast, and Other Cancers and Tumors at RAF 0.186 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 documentation supports C49.4?

This code is for soft tissue sarcomas of the abdomen; ensure the tumor is in soft tissue, not in abdominal organs Document whether the tumor is in the abdominal wall or deeper abdominal structures for clinical context Because C49.4 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. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM C49.4: Malignant neoplasm

C49.4 maps to CMS-HCC V28 23 (RAF 0.186). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software

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Code lookupC49.4Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C49.4

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

Malignant neoplasm of connective and soft tissue of abdomen

A malignant (cancerous) tumor that develops in the soft tissues or connective tissues of the abdominal wall or cavity, such as muscles, fat, or fibrous tissue.

Buddy Insight

Malignant neoplasm of connective and soft tissue of the abdomen includes sarcomas of the abdominal wall musculature and soft tissues.

CMS-HCC V28

Mapped

HCC 23

Prostate, Breast, and Other C...

RAF 0.186

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

C49Malignant neoplasm of other connective and soft tissue

C49.4Malignant neoplasm of connective and soft tissue of abdomen

Inclusion Terms

Official

Malignant neoplasm of abdominal wall
Malignant neoplasm of hypochondrium

Excludes 2

Official

Kaposi's sarcoma of soft tissue (C46.1)
malignant neoplasm of heart (C38.0)
malignant neoplasm of peripheral nerves and autonomic nervous system (C47.-)
malignant neoplasm of peritoneum (C48.2)
malignant neoplasm of retroperitoneum (C48.0)

Related Child Codes

Official

C49.0Malignant neoplasm of connective and soft tissue of head, face and neck

C49.1Malignant neoplasm of connective and soft tissue of upper limb, including shoulder

C49.2Malignant neoplasm of connective and soft tissue of lower limb, including hip

C49.3Malignant neoplasm of connective and soft tissue of thorax

C49.5Malignant neoplasm of connective and soft tissue of pelvis

Includes

Official

malignant neoplasm of blood vessel
malignant neoplasm of bursa
malignant neoplasm of cartilage
malignant neoplasm of fascia
malignant neoplasm of fat

Excludes 1

Official

malignant neoplasm of cartilage (of):
articular (C40-C41)
larynx (C32.3)
nose (C30.0)
malignant neoplasm of connective tissue of breast (C50.-)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C49.4 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C49.4 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C49.4 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Pathology confirming malignant soft tissue neoplasm of the abdominal wall or abdominal soft tissue

Specific location (anterior wall, flank, abdominal musculature)

Distinction from retroperitoneal tumors (C48.0) and intra-abdominal organ tumors

Histological subtype and tumor grade

MEAT Support

HCC Buddy guidance

Pathology confirming malignant soft tissue neoplasm of the abdominal wall or abdominal soft tissue

Specific location (anterior wall, flank, abdominal musculature)

Distinction from retroperitoneal tumors (C48.0) and intra-abdominal organ tumors

Histological subtype and tumor grade

Audit Caution

HCC Buddy guidance

Confusing abdominal wall soft tissue sarcomas with retroperitoneal sarcomas — the latter carry a significantly higher RAF weight in V24

Coding desmoid tumors (aggressive fibromatosis) as malignant — desmoid tumors are coded as D48.1 (uncertain behavior)

Not distinguishing between nerve-origin tumors (C47.4) and general soft tissue tumors (C49.4)

Using this code for intra-abdominal organ cancers that have their own specific codes

Common Mistakes

HCC Buddy guidance

C48.0 (Malignant neoplasm of retroperitoneum) — retroperitoneal tumors, not abdominal wall; note C48.0 maps to HCC 9 with much higher RAF

C47.4 (Peripheral nerves of abdomen) — nerve-origin abdominal tumor

C49.A_ (Gastrointestinal stromal tumors) — GIST is a distinct tumor type

D21.4 (Benign neoplasm of connective/soft tissue of abdomen) — benign counterpart

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 C49.4 an HCC code?

Yes. C49.4 (Malignant neoplasm of connective and soft tissue of abdomen) maps to Prostate, Breast, and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model (and Lymphoma and Other Cancers under V24), with a community non-dual aged RAF of 0.186. It is billable for payment year 2026.

Coder answer: C49.4 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: C49.4
Description: Malignant neoplasm of connective and soft tissue of abdomen
HCC (V28): HCC 23 — Prostate, Breast, and Other Cancers and Tumors
RAF: 0.186
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 23, Prostate, Breast, and Other Cancers and Tumors

0.186

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 C49.4 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C49.4

For C49.4 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 C49.4 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C49.4 is the ICD-10-CM diagnosis code for malignant neoplasm of connective and soft tissue of abdomen. A malignant (cancerous) tumor that develops in the soft tissues or connective tissues of the abdominal wall or cavity, such as muscles, fat, or fibrous tissue. C49.4 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, C49.4 maps to Prostate, Breast, and Other Cancers and Tumors (HCC 23) with a community, non-dual, aged base RAF weight of 0.186. Under the older CMS-HCC V24 model, C49.4 maps to Lymphoma and Other Cancers (HCC 10) with a community, non-dual, aged base RAF weight of 0.675. 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 is for soft tissue sarcomas of the abdomen; ensure the tumor is in soft tissue, not in abdominal organs. Because C49.4 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 C49.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This code is for soft tissue sarcomas of the abdomen; ensure the tumor is in soft tissue, not in abdominal organs
•Document whether the tumor is in the abdominal wall or deeper abdominal structures for clinical context

Clinical Significance

Malignant neoplasm of connective and soft tissue of the abdomen includes sarcomas of the abdominal wall musculature and soft tissues. These must be carefully distinguished from retroperitoneal sarcomas (C48.0) and intra-abdominal organ malignancies, as the treatment approach and HCC impact differ significantly.

Documentation Requirements

✓Pathology confirming malignant soft tissue neoplasm of the abdominal wall or abdominal soft tissue
✓Specific location (anterior wall, flank, abdominal musculature)
✓Distinction from retroperitoneal tumors (C48.0) and intra-abdominal organ tumors
✓Histological subtype and tumor grade
✓Imaging confirming abdominal wall or soft tissue origin rather than visceral origin

Commonly Confused Codes

•C48.0 (Malignant neoplasm of retroperitoneum): retroperitoneal tumors, not abdominal wall; note C48.0 maps to HCC 9 with much higher RAF
•C47.4 (Peripheral nerves of abdomen): nerve-origin abdominal tumor
•C49.A_ (Gastrointestinal stromal tumors): GIST is a distinct tumor type
•D21.4 (Benign neoplasm of connective/soft tissue of abdomen): benign counterpart