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C7A.024 ICD-10-CM Code: Malignant carcinoid tumor of the descending colon

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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neuroendocrine tumors (C7A)

C7A.024

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

Malignant carcinoid tumor of the descending colon

A rare cancer that develops in hormone-producing cells of the descending colon, the downward section of the large intestine on the left side of the abdomen.

Buddy the Bee presenting code insight

Buddy Insight

Malignant carcinoid tumor of the descending colon is a rare hindgut neuroendocrine neoplasm.

CMS-HCC V28

HCC 21

RAF 0.545

CMS-HCC V24

HCC 12

RAF 0.150

ACA/HHS

0

0

RAF 0

ESRD/PACE

HCC 12

RAF 0.0

RXHCC

HCC 22

RAF 0.0

Code Trumping

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Code Book Path

Official
C7A.0Malignant carcinoid tumors
C7A.02Malignant carcinoid tumors of the appendix, large intestine, and rectum
C7A.024Malignant carcinoid tumor of the descending colon

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C7A.024 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C7A.024 in this effective period.

Related Child Codes

Official
C7A.020Malignant carcinoid tumor of the appendix
C7A.021Malignant carcinoid tumor of the cecum
C7A.022Malignant carcinoid tumor of the ascending colon
C7A.023Malignant carcinoid tumor of the transverse colon
C7A.025Malignant carcinoid tumor of the sigmoid colon

Includes

Official

ICD-10-CM does not list Includes notes for C7A.024 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C7A.024 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C7A.024 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C7A.024 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C7A.024 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Pathological confirmation with neuroendocrine markers
WHO tumor grade — Ki-67 index and mitotic rate
Tumor size, depth of invasion, and margin status
Colonoscopy confirming descending colon location

MEAT Support

HCC Buddy guidance
Pathological confirmation with neuroendocrine markers
WHO tumor grade — Ki-67 index and mitotic rate
Tumor size, depth of invasion, and margin status
Colonoscopy confirming descending colon location

Audit Caution

HCC Buddy guidance
Using adenocarcinoma codes for a carcinoid tumor — histological type determines the code category
Confusing descending colon with sigmoid colon location — colonoscopy or operative findings clarify the boundary
Not grading the tumor to determine whether it is benign or malignant by WHO criteria
Missing the hindgut origin significance — these tumors rarely cause carcinoid syndrome

Common Mistakes

HCC Buddy guidance
C18.6 — Primary malignant neoplasm of descending colon; adenocarcinoma uses C18 codes
C7A.023 — Malignant carcinoid tumor of transverse colon; located proximal to the descending colon
C7A.025 — Malignant carcinoid tumor of sigmoid colon; sigmoid is distal to the descending colon
D3A.024 — Benign carcinoid tumor of descending colon; verify malignant versus benign behavior

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is C7A.024 an HCC code?

Yes. C7A.024 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model (and Breast, Prostate, and Other Cancers and Tumors under V24).

HCC Category Mapping

V28HCC 21, Breast, Prostate, Colorectal and Other Cancers and Tumors
0.545
V24HCC 12, Breast, Prostate, and Other Cancers and Tumors
0.150
ESRDHCC 12, Breast, Prostate, and Other Cancers and Tumors
0.000
RxHCCHCC 22, Cancer, Other Specified Sites
0.000

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 C7A.024

For C7A.024to 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 C7A.024 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

C7A.024 is the ICD-10-CM diagnosis code for malignant carcinoid tumor of the descending colon. A rare cancer that develops in hormone-producing cells of the descending colon, the downward section of the large intestine on the left side of the abdomen. C7A.024 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neuroendocrine tumors (c7a).

Under the CMS-HCC V28 risk adjustment model, C7A.024 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C7A.024 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.

The descending colon runs vertically down the left side of the abdomen; note that C7A.023 is not used (gap in code sequence). Because C7A.024 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 C7A.024 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •The descending colon runs vertically down the left side of the abdomen; note that C7A.023 is not used (gap in code sequence)
  • •Document whether the tumor is in the descending colon proper or extends into the sigmoid region

Clinical Significance

Malignant carcinoid tumor of the descending colon is a rare hindgut neuroendocrine neoplasm. Hindgut carcinoids (descending colon, sigmoid, rectum) are less likely to produce serotonin and cause carcinoid syndrome compared to midgut tumors. However, they can still metastasize and require surgical resection with careful pathological staging.

Documentation Requirements

  • ✓Pathological confirmation with neuroendocrine markers
  • ✓WHO tumor grade — Ki-67 index and mitotic rate
  • ✓Tumor size, depth of invasion, and margin status
  • ✓Colonoscopy confirming descending colon location
  • ✓Staging workup — CT abdomen/pelvis, liver assessment
  • ✓Surgical approach and extent of resection

Commonly Confused Codes

  • •C18.6 — Primary malignant neoplasm of descending colon; adenocarcinoma uses C18 codes
  • •C7A.023 — Malignant carcinoid tumor of transverse colon; located proximal to the descending colon
  • •C7A.025 — Malignant carcinoid tumor of sigmoid colon; sigmoid is distal to the descending colon
  • •D3A.024 — Benign carcinoid tumor of descending colon; verify malignant versus benign behavior

Child Codes

C7A.020Malignant carcinoid tumor of the appendix
HCC 21
C7A.021Malignant carcinoid tumor of the cecum
HCC 21
C7A.022Malignant carcinoid tumor of the ascending colon
HCC 21
C7A.023Malignant carcinoid tumor of the transverse colon
HCC 21
C7A.024Malignant carcinoid tumor of the descending colon
HCC 21
C7A.025Malignant carcinoid tumor of the sigmoid colon
HCC 21
C7A.026Malignant carcinoid tumor of the rectum
HCC 21
C7A.029Malignant carcinoid tumor of the large intestine, unspecified portion
HCC 21

Code Hierarchy

└C7AMalignant neuroendocrine tumors└C7A.0Malignant carcinoid tumors└C7A.02Malignant carcinoid tumors of the appendix, large intestine, and rectum└C7A.024Malignant carcinoid tumor of the descending colon
└C7A.024Malignant carcinoid tumor of the descending colon

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