2027 ICD-10-CM Diagnosis Code C80.0Disseminated malignant neoplasm, unspecified
ICD-10-CM Codes›C00–D49›C76-C80›C80
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 18
- Chronic Condition
C80.0 is a billable ICD-10-CM diagnosis code for disseminated malignant neoplasm, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 826 through 830, 843 through 845. 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 19 closely related codes. Coders also document this condition as adenocarcinoma carcinomatosis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Malignant neoplasm, unspecified.
For Medicare Advantage risk adjustment, C80.0 maps to CMS-HCC Category 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid) under the V28 model, adding a risk factor of about 2.341 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C80.0 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 2027.
Source: CMS Payment Year 2027 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 carcinomatosis
- Carcinomatosis
- Chorea due to widespread metastatic malignant neoplastic disease
- Melanoma carcinomatosis
- Metastatic small cell neuroendocrine carcinoma
- Multiple malignancy
- Small cell carcinoma carcinomatosis
- Squamous cell carcinomatosis
- Undifferentiated large cell carcinomatosis
- Widespread metastatic malignant neoplastic disease
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C80.0: its own notes plus those printed at C80 and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Carcinomatosis NOS
- Generalized cancer, unspecified site (primary) (secondary)
- Generalized malignancy, unspecified site (primary) (secondary)
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Notes
General instructions on how these codes are used.
- Functional activity
- All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
- Morphology [Histology]
- Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
- Primary malignant neoplasms overlapping site boundaries
- A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
- Malignant neoplasm of ectopic tissue
- Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name C80.0, its category, or a range that includes it.
Excludes1 2
These codes carry an Excludes1 note naming C80.0: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Carcinoma (malignant) See Also: Neoplasm, by site, malignant;
Carcinomatosis C80.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Disseminated Malignant Neoplasm
cancer that is spread throughout the body, a metastatic phenomenon.
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. |
|---|---|---|---|---|---|---|
| disease, generalized | C80.0 | – | – | – | – | – |
| disseminated | C80.0 | – | – | – | – | – |
| generalized | C80.0 | – | – | – | – | – |
Patient EducationClinical
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Read the full article at MedlinePlus
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Convert C80.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C80.0Overview
What is the ICD-10 code for disseminated malignant neoplasm, unspecified?
The ICD-10-CM code for disseminated malignant neoplasm, unspecified is C80.0 (sometimes written as C800). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is C80.0 (Malignant neoplasm without specification of site) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report disseminated malignant neoplasm, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does C80.0 group to?
When disseminated malignant neoplasm, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 844, 827, 829, 843, 828, 826, 830, 845, with relative weights from 0.8443 to 4.7560 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C80.0 a CC or MCC?
CMS lists C80.0 as a CC (complication or comorbidity) for FY 2027. 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 19 closely related codes in its exclusion list.
Can C80.0 be reported with C7A.00?
Not as a rule. The Excludes1 note at C80, which applies to C80.0, lists "malignant carcinoid tumor of unspecified site (C7A.00)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is C80.0?
C80.0 (disseminated malignant neoplasm, unspecified) maps to CMS-HCC Category 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid), commonly written as HCC 18, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 8 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 20.
Does C80.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C80.0 adds a risk adjustment factor of about 2.341 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 1.110 to 2.537 depending on the payment segment). A more severe related category (HCC 17) supersedes it when both are reported. See the full factor table on the HCC 18 category page.
