E84.0 vs Q33.0
E84.0 and Q33.0 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 Q33.0
cystic fibrosis (E84.0)
E84.0
Cystic fibrosis with pulmonary manifestations
Billable
- Chapter 4
- Endocrine, nutritional and metabolic diseases
- Section
- E70-E88
Indexed under
- Fibrosis, fibrotic › cystic › with › pulmonary manifestations
Q33.0
Congenital cystic lung
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q30-Q34
Use when the record says
- Congenital cystic lung disease
- Congenital honeycomb lung
- Congenital polycystic lung disease
Indexed under
- Honeycomb lung › congenital
- Cyst › bronchogenic › congenital (colloid) (mucous) (simple) (retention)
- Cyst › congenital NEC › lung (colloid) (mucous) (simple) (retention)
- Cyst › lung › congenital (colloid) (mucous) (simple) (retention)
- Cystic › lung disease › congenital
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