2027 ICD-10-CM Diagnosis Code N63.31Unspecified lump in axillary tail of the right breast

ICD-10-CM Codes›N00–N99›N60-N65›N63

ICD-10-CM N63.31
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N63.31 is a billable ICD-10-CM diagnosis code for unspecified lump in axillary tail of the right breast. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 600 through 601. Coders also document this condition as lump of axillary tail of right breast. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nonmalignant breast conditions.

Code Identity

ICD-10-CM Code
N63.31
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified lump in axillary tail of the right breast
Short Description
Unspecified lump in axillary tail of the right breast
Same as the full description in the CMS dataset.
Parent Code
N63.3
Unspecified lump in axillary tail

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN60-N65Disorders of breast
CategoryN63Unspecified lump in breast
This CodeN63.31Unspecified lump in axillary tail of the right breast

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Lump of axillary tail of right breast

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N63.31: its own notes plus those printed at block N60-N65 and Chapter 14. 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.

From Block N60-N65 Disorders of breast applies to 60 codes
  • disorders of breast associated with childbirth (O91-O92)

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 Chapter 14 (N00-N99) Diseases of the genitourinary system applies to 838 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name N63.31, its category, or a range that includes it.

Excludes2 2

These codes carry an Excludes2 note naming N63.31: its condition is not part of those codes, and both may be reported when the patient has both.

  • Chapter 18 (R00-R99) Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
    signs and symptoms of breast (N63, N64.5) names N63, which includes this code
  • R22.2 Localized swelling, mass and lump, trunk
    breast mass and lump (N63) names N63, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR GEN017
Nonmalignant breast conditions
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Breast Diseases

Breast diseases include various conditions and changes in your breast. Most women experience breast changes at some time. Your age, hormone levels, and medicines you take may cause lumps, bumps, and discharges of fluids that are not breast milk.

The full article covers:

  • What are breast diseases?
  • What are the symptoms of breast disease?
  • How are breast diseases diagnosed?
  • What are the treatments for breast disease?

Read the full article at MedlinePlus

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

Convert N63.31 to ICD-9-CMHistory

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

ICD-9-CM
611.72 Lump or mass in breast
Approximate The match is approximate rather than exact.

Code History & ChangesHistory

Replacement N63.31 replaces the following previously assigned code(s):

  • N63 - Unspecified lump in breast
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N63.31Overview

What is the ICD-10 code for unspecified lump in axillary tail of the right breast?

The ICD-10-CM code for unspecified lump in axillary tail of the right breast is N63.31 (sometimes written as N6331). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is N63.31 (Unspecified lump in axillary tail) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified lump in axillary tail of the right breast on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does N63.31 group to?

When unspecified lump in axillary tail of the right breast is the principal diagnosis on an inpatient stay, it groups to MS-DRG 600, 601, with relative weights from 0.6014 to 0.9971 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N63.31?

Under the General Equivalence Mappings, unspecified lump in axillary tail of the right breast converts to ICD-9-CM 611.72 (lump or mass in breast). The mapping is approximate, so confirm the match fits the documentation.