ICD-10-CM 2027
ICD-10 code for mastitis
From the official ICD-10-CM alphabetic index entry “Mastitis (acute) (diffuse) (nonpuerperal) (subacute)”. Page updated September 29, 2026.
About coding mastitis
The ICD-10-CM code for mastitis is N61.0 (Mastitis without abscess). The official index lists 13 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on N61.0.
Within N61, choose N61.0 (Mastitis without abscess) only when documentation doesn't support a more specific option: abscess of the breast and nipple (N61.1) and granulomatous mastitis (N61.2).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 600 (Non-Malignant Breast Disorders with CC/MCC, relative weight 0.9975) and DRG 601 (Non-Malignant Breast Disorders without CC/MCC, relative weight 0.6017), in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific mastitis codes (official index)
- with abscess N61.1 — Abscess of the breast and nipple
- chronic (cystic)
- cystic (Schimmelbusch's type)
- fibrocystic
- granulomatous N61.2 — Granulomatous mastitis
- infective N61.0 — Mastitis without abscess
- newborn P39.0 — Neonatal infective mastitis
- interstitial, gestational or puerperal
- neonatal (noninfective) P83.4 — Breast engorgement of newborn
- infective P39.0 — Neonatal infective mastitis
- obstetric (interstitial) (nonpurulent)
- associated with
- lactation O91.23 — Nonpurulent mastitis associated with lactation
- pregnancy O91.21 — Nonpurulent mastitis associated with pregnancy
- puerperium O91.22 — Nonpurulent mastitis associated with the puerperium
- purulent
- associated with
- lactation O91.13 — Abscess of breast associated with lactation
- pregnancy O91.11 — Abscess of breast associated with pregnancy
- puerperium O91.12 — Abscess of breast associated with the puerperium
- periductal
- phlegmonous
- plasma cell
- without abscess N61.0 — Mastitis without abscess
Common questions about mastitis ICD-10 codes
What is the ICD-10 code for mastitis?
- N61.0 — Mastitis without abscess. More specific codes apply when the documentation supports them: N61.1, N61.2, N61.0, P39.0 and others below.
What is the ICD-10 code for granulomatous mastitis?
- N61.2 — Granulomatous mastitis (header code; choose a more specific subcode).
What is the ICD-10 code for infective mastitis?
- N61.0 — Mastitis without abscess.
What is the ICD-10 code for neonatal mastitis?
- P83.4 — Breast engorgement of newborn.
Is N61.0 billable?
- Yes. N61.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can N61.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict N61.0 as a principal diagnosis.
Is N61.0 a CC or MCC?
- No. N61.0 is neither a CC nor an MCC under MS-DRG v44.0.