D28 vs Q50.4
D28 and Q50.4 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on D28
fimbrial cyst (Q50.4)
D28
Benign neoplasm of other and unspecified female genital organs
Not billable
- Chapter 2
- Neoplasms
- Section
- D10-D36
Use when the record says
- adenomatous polyp
- benign neoplasm of skin of female genital organs
- benign teratoma
Q50.4
Embryonic cyst of fallopian tube
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q50-Q56
Use when the record says
- Fimbrial cyst
Indexed under
- Fimbrial cyst
- Cyst › fimbrial (colloid) (mucous) (simple) (retention)
- Cyst › Müllerian duct (colloid) (mucous) (simple) (retention)
- Cyst › paramesonephric duct (colloid) (mucous) (simple) (retention)
- Cyst › congenital NEC › fallopian tube (colloid) (mucous) (simple) (retention)
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027