2027 ICD-10-CM Diagnosis Code N61.21Granulomatous mastitis, right breast

ICD-10-CM Codes›N00–N99›N60-N65›N61

ICD-10-CM N61.21
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N61.21 is a billable ICD-10-CM diagnosis code for granulomatous mastitis, 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 granulomatous mastitis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nonmalignant breast conditions.

Code Identity

ICD-10-CM Code
N61.21
Billable Status
Yes — Valid for Submission
Code Describes
Granulomatous mastitis, right breast
Short Description
Granulomatous mastitis, right breast
Same as the full description in the CMS dataset.
Parent Code
N61.2
Granulomatous mastitis

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN60-N65Disorders of breast
CategoryN61Inflammatory disorders of breast
This CodeN61.21Granulomatous mastitis, right breast

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Granulomatous mastitis
  • Granulomatous mastitis of right breast

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N61.21: its own notes plus those printed at N61, 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 N61 Inflammatory disorders of breast applies to 6 codes
  • inflammatory carcinoma of breast (C50.A-)
  • inflammatory disorder of breast associated with childbirth (O91.-)
  • neonatal infective mastitis (P39.0)
  • thrombophlebitis of breast [Mondor's disease] (I80.8)
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.

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Granulomatous Mastitis

    a rare, benign, inflammatory breast disease occurring in premenopausal women shortly after a recent pregnancy. the origin is unknown but it is commonly mistaken for malignancy and sometimes associated with breast feeding and the use of oral contraceptives.

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.

Code History & ChangesHistory

Replacement N61.21 replaces the following previously assigned code(s):

  • N61.0 - Mastitis without abscess
FY 2021AddedAdded to the ICD-10-CM code setEffective October 1, 2020.
FY 2022–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N61.21Overview

What is the ICD-10 code for granulomatous mastitis, right breast?

The ICD-10-CM code for granulomatous mastitis, right breast is N61.21 (sometimes written as N6121). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is N61.21 (Granulomatous mastitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report granulomatous mastitis, right breast on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does N61.21 group to?

When granulomatous mastitis, 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.

Can N61.21 be reported with a code from C50.A?

Not as a rule. The Excludes1 note at N61, which applies to N61.21, lists "inflammatory carcinoma of breast (C50.A-)". 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).