Excludes1 pair
F84.2 vs F84.3
F84.2 and F84.3 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on F84.2
Other childhood disintegrative disorder (F84.3)
F84.2
Rett's syndrome
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F80-F89
Indexed under
- Rett's disease or syndrome
F84.3
Other childhood disintegrative disorder
Billable
- Chapter 5
- Mental, Behavioral and Neurodevelopmental disorders
- Section
- F80-F89
Use when the record says
- Dementia infantilis
- Disintegrative psychosis
- Heller's syndrome
- Symbiotic psychosis
Indexed under
- Heller's disease or syndrome
- Dementia › infantile, infantilis
- Disorder › childhood disintegrative NEC
- Disorder › disintegrative, childhood NEC
- Psychosis, psychotic › disintegrative (childhood)
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