2026 ICD-10-CM Diagnosis Code C19Malignant neoplasm of rectosigmoid junction
ICD-10-CM Codes›C00–D49›C15-C26›C19
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 22
- Chronic Condition
C19 is a billable ICD-10-CM diagnosis code for malignant neoplasm of rectosigmoid junction. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 374 through 376. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 21 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - colorectal.
For Medicare Advantage risk adjustment, C19 maps to CMS-HCC Category 22 (Bladder, Colorectal, and Other Cancers) under the V28 model, adding a risk factor of about 0.363 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C19 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Adenocarcinoma of rectosigmoid junction
- Adenocarcinoma of rectum
- Adenocarcinoma of sigmoid colon
- Anorectal adenocarcinoma
- Carcinoma of rectosigmoid junction
- Carcinoma of sigmoid colon
- Malignant colorectal neoplasm
- Malignant neoplasm of colorectum expressing human epidermal growth factor 2
- Malignant neoplasm of rectosigmoid junction
- Malignant neoplasm of rectum, rectosigmoid junction and anus
- Microsatellite instability-high colorectal cancer
- Microsatellite instability-high solid malignant tumor
- Primary adenocarcinoma of colon
- Primary adenocarcinoma of rectosigmoid junction
- Primary carcinoma of colon
- Primary carcinoma of rectosigmoid junction
- Primary carcinoma of sigmoid colon
- Primary malignant neoplasm of rectosigmoid junction
- Primary malignant neoplasm of rectum
- Primary malignant neoplasm of sigmoid colon
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Malignant neoplasm of colon with rectum
- Malignant neoplasm of rectosigmoid (colon)
Type 1 Excludes
- malignant carcinoid tumors of the colon C7A.02
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
| Site | Malig. Primary | Malig. Secondary | Ca in situ | Benign | Uncertain | Unspec. |
|---|---|---|---|---|---|---|
| colon [See Also: Neoplasm, intestine, large] › with rectum | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
| intestine, intestinal › large › colon › and rectum | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
| junction › pelvirectal | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
| junction › rectosigmoid | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
| pelvirectal junction | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
| rectosigmoid (junction) | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
| rectum (ampulla) › and colon | C19 | C78.5 | D01.1 | D12.7 | D37.5 | D49.0 |
Patient EducationClinical
Colorectal Cancer
Colorectal cancer is cancer that develops in the tissues of the colon or rectum. Your colon and rectum are part of your digestive system:
The full article covers:
- What is colorectal cancer?
- What causes colorectal cancer?
- Who is more likely to develop colorectal cancer?
- What are the symptoms of colorectal cancer?
- What is screening for colorectal cancer and who needs it?
- How is colorectal cancer diagnosed?
- What are the treatments for colorectal cancer?
- Can colorectal cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C19 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C19Overview
What is the ICD-10 code for malignant neoplasm of rectosigmoid junction?
The ICD-10-CM code for malignant neoplasm of rectosigmoid junction is C19. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is C19 (Malignant neoplasm of rectosigmoid junction) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of rectosigmoid junction on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C19 group to?
When malignant neoplasm of rectosigmoid junction is the principal diagnosis on an inpatient stay, it groups to MS-DRG 374, 375, 376, with relative weights from 0.9243 to 2.1387 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C19 a CC or MCC?
CMS lists C19 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 21 closely related codes in its exclusion list.
What is the ICD-9 equivalent of C19?
Under the General Equivalence Mappings, malignant neoplasm of rectosigmoid junction converts to ICD-9-CM 154.0 (mal neo rectosigmoid jct). The mapping is a direct match.
What HCC is C19?
C19 (malignant neoplasm of rectosigmoid junction) maps to CMS-HCC Category 22 (Bladder, Colorectal, and Other Cancers), commonly written as HCC 22, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 11 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does C19 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C19 adds a risk adjustment factor of about 0.363 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.314 to 0.410 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, HCC 20, and HCC 21) supersedes it when both are reported. See the full factor table on the HCC 22 category page.
