ICD-10-CM 2027
ICD-10 code for breast disorder
From the official ICD-10-CM alphabetic index entry “Disorder (of) › breast”. Page updated September 29, 2026.
About coding breast disorder
The ICD-10-CM code for breast disorder is N64.9 (Disorder of breast, unspecified). The official index lists 9 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on N64.9.
Within N64, choose N64.9 (Disorder of breast, unspecified) only when documentation doesn't support a more specific option: fissure and fistula of nipple (N64.0), fat necrosis of breast (N64.1), atrophy of breast (N64.2), Galactorrhea not associated with childbirth (N64.3), Mastodynia (N64.4), other signs and symptoms in breast (N64.5) and other specified disorders of breast (N64.8).
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 breast disorder codes (official index)
- agalactia
- associated with
- lactation O92.70 — Unspecified disorders of lactation
- specified NEC O92.79 — Other disorders of lactation
- pregnancy O92.20 — Unspecified disorder of breast associated with pregnancy and the puerperium
- specified NEC O92.29 — Other disorders of breast associated with pregnancy and the puerperium
- puerperium O92.20 — Unspecified disorder of breast associated with pregnancy and the puerperium
- specified NEC O92.29 — Other disorders of breast associated with pregnancy and the puerperium
- cracked nipple
- galactorrhea
- hypogalactia O92.4 — Hypogalactia
- lactation disorder NEC O92.79 — Other disorders of lactation
- mastitis
- nipple infection
- retracted nipple
- specified type NEC N64.89 — Other specified disorders of breast
Common questions about breast disorder ICD-10 codes
What is the ICD-10 code for breast disorder?
- N64.9 — Disorder of breast, unspecified. More specific codes apply when the documentation supports them: O92.70, O92.79, O92.20, O92.29 and others below.
What is the ICD-10 code for hypogalactia breast disorder?
- O92.4 — Hypogalactia.
What is the ICD-10 code for lactation disorder nec breast disorder?
- O92.79 — Other disorders of lactation.
Is N64.9 billable?
- Yes. N64.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can N64.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict N64.9 as a principal diagnosis.
Is N64.9 a CC or MCC?
- No. N64.9 is neither a CC nor an MCC under MS-DRG v44.0.