2026 ICD-10-CM Diagnosis Code D37.3Neoplasm of uncertain behavior of appendix

ICD-10-CM Codes›C00–D49›D37-D48›D37

ICD-10-CM D37.3
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D37.3 is a billable ICD-10-CM diagnosis code for neoplasm of uncertain behavior of appendix. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neoplasms of unspecified nature or uncertain behavior.

Code Identity

ICD-10-CM Code
D37.3
Billable Status
Yes — Valid for Submission
Code Describes
Neoplasm of uncertain behavior of appendix
Short Description
Neoplasm of uncertain behavior of appendix
Same as the full description in the CMS dataset.
Parent Code
D37
Neoplasm of uncertain behavior of oral cavity and digestive organs

Code Classification

ChapterC00–D49Neoplasms
SectionD37-D48Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes
CategoryD37Neoplasm of uncertain behavior of oral cavity and digestive organs
This CodeD37.3Neoplasm of uncertain behavior of appendix

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Neoplasm of uncertain behavior of appendix

Clinical ClassificationClinical

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

CCSR NEO072
Neoplasms of unspecified nature or uncertain behavior
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Appendiceal Neoplasms

    tumors or cancer of the appendix.

  • Appendix

    a worm-like blind tube extension from the cecum.

  • Colon

    the segment of large intestine between the cecum and the rectum. it includes the ascending colon; the transverse colon; the descending colon; and the sigmoid colon.

Table of NeoplasmsClinical

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

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
appendixC18.1C78.5D01.0D12.1D37.3D49.0
intestine, intestinal › large › appendixC18.1C78.5D01.0D12.1D37.3D49.0

Patient EducationClinical

Colonic Diseases

Your colon, also known as the large intestine, is part of your digestive system. It's a long, hollow tube at the end of your digestive tract where your body makes and stores stool. Many disorders affect the colon's ability to work properly. Some of these include:

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert D37.3 to ICD-9-CMHistory

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

ICD-9-CM
235.2 Unc behav neo intestine
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D37.3Overview

Is D37.3 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report neoplasm of uncertain behavior of appendix on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D37.3 group to?

When neoplasm of uncertain behavior of appendix 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.

What is the ICD-9 equivalent of D37.3?

Under the General Equivalence Mappings, neoplasm of uncertain behavior of appendix converts to ICD-9-CM 235.2 (unc behav neo intestine). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.