2027 ICD-10-CM Diagnosis Code C26.1Malignant neoplasm of spleen

ICD-10-CM Codes›C00–D49›C15-C26›C26

ICD-10-CM C26.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

C26.1 is a billable ICD-10-CM diagnosis code for malignant neoplasm of spleen. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 820 through 825, 840 through 842. Coders also document this condition as angiosarcoma of spleen. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - all other types.

For Medicare Advantage risk adjustment, C26.1 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 2027.

Code Identity

ICD-10-CM Code
C26.1
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of spleen
Short Description
Malignant neoplasm of spleen
Same as the full description in the CMS dataset.
Parent Code
C26
Malignant neoplasm of other and ill-defined digestive organs

Code Classification

ChapterC00–D49Neoplasms
SectionC15-C26Malignant neoplasms of digestive organs
CategoryC26Malignant neoplasm of other and ill-defined digestive organs
This CodeC26.1Malignant neoplasm of spleen

Medicare Risk Adjustment (HCC)Billing

C26.1 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.

CMS-HCC V28 Category (Payment Model)
HCC 22— Bladder, Colorectal, and Other Cancers
Payment HCC · PY 2027 one of 126 ICD-10-CM codes in this category
Risk Adjustment Factor (RAF) Weight
+0.363
community, non-dual, aged · ranges 0.314–0.410 across segments
Hierarchy
Superseded by HCC 17, HCC 18, HCC 19, HCC 20, and HCC 21
a more severe related category takes the payment when both are reported
Prior Model (CMS-HCC V24)
HCC 11
V24 retired V28 pays 100% of MA risk scores since PY 2026
Other CMS Models
PACE (CMS-HCC V22): HCC 11 · ESRD (V21): HCC 11 · ESRD (V24): HCC 11
ESRD V21 weights: 0.076 dialysis, 0.284–0.298 functioning graft · ESRD V24 weights: 0.059 dialysis, 0.257–0.362 functioning graft
Part D (RxHCC)
Not mapped
C26.1 does not risk-adjust in the RxHCC prescription drug model

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.

  • Angiosarcoma of spleen
  • Fibrosarcoma
  • Fibrosarcoma of spleen
  • Malignant neoplasm of spleen
  • Primary fibrosarcoma of spleen
  • Primary malignant neoplasm of spleen

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to C26.1: its own notes plus those printed at C26, block C15-C26, and Chapter 2. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

On C26.1 itself
From C26 Malignant neoplasm of other and ill-defined digestive organs applies to 3 codes
  • malignant neoplasm of peritoneum and retroperitoneum (C48.-)
From Block C15-C26 Malignant neoplasms of digestive organs applies to 60 codes
  • Kaposi's sarcoma of gastrointestinal sites (C46.4)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block C15-C26 Malignant neoplasms of digestive organs applies to 60 codes
  • gastrointestinal stromal tumors (C49.A-)

Notes

General instructions on how these codes are used.

From Chapter 2 (C00-D49) Neoplasms applies to 1,730 codes
  • 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 C26.1, its category, or a range that includes it.

Applicable To 1

These notes mention C26.1.

  • Z80.0 Family history of malignant neoplasm of digestive organs
    Conditions classifiable to C15-C26 names C15-C26, which includes this code

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO021
Gastrointestinal cancers - all other types
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Malignant Splenic Neoplasm

    a malignant neoplasm affecting the spleen. representative examples include leukemias, lymphomas, and sarcomas.

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
spleen, splenic NECC26.1C78.89D01.7D13.99D37.8D49.0

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Convert C26.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
159.1 Malignant neo spleen NEC
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About C26.1Overview

What is the ICD-10 code for malignant neoplasm of spleen?

The ICD-10-CM code for malignant neoplasm of spleen is C26.1 (sometimes written as C261). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is C26.1 (Malignant neoplasm of other and ill-defined digestive organs) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of spleen on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does C26.1 group to?

When malignant neoplasm of spleen is the principal diagnosis on an inpatient stay, it groups to MS-DRG 841, 821, 822, 825, 842, 824, 840, 820, 823, with relative weights from 0.9948 to 6.2454 depending on complications. Higher weights mean higher Medicare reimbursement.

Can C26.1 be reported with a code from C81?

Not as a rule. The Excludes1 note on C26.1 lists "Hodgkin lymphoma (C81.-)". 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 is the ICD-9 equivalent of C26.1?

Under the General Equivalence Mappings, malignant neoplasm of spleen converts to ICD-9-CM 159.1 (malignant neo spleen NEC). The mapping is a direct match.

What HCC is C26.1?

C26.1 (malignant neoplasm of spleen) 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 2027. 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 C26.1 risk-adjust for Medicare Advantage payment?

Yes. When documented and reported on a Medicare Advantage encounter, C26.1 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.