N61.21
Granulomatous mastitis, right breast
N61.21 (also written N6121) is a billable ICD-10-CM diagnosis code for granulomatous mastitis, right breast. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 6 codes in category N61 (Inflammatory disorders of breast). Its coding notes include 5 Excludes1 entries and 8 Excludes2 entries.
Excludes1
Not coded here. The listed conditions generally should not be reported together.
Also from chapter/block level (1 note)
- disorders of breast associated with childbirth (O91-O92)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
Also from chapter/block level (8 notes)
- 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)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the MMTA - Other clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026