ICD-10 F84.2
Billable / Specific CCRett's syndrome
About ICD-10-CM F84.2
ICD-10-CM code F84.2 represents Rett's syndrome. This is a billable/specific code in the Mental, Behavioral, and Neurodevelopmental chapter (block F84). The 2026 edition of ICD-10-CM F84.2 became effective on October 1, 2025.
Coding Tips for F84.2
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
F84.2 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Type 1 Excludes
Pure excludes, these codes can never be coded together with F84.2. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- Asperger's syndrome (F84.5)
- Autistic disorder (F84.0)
- Other childhood disintegrative disorder (F84.3)
Inpatient DRG Impact, CC
codes Rett's syndrome. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for F84.2
Local Coverage Determinations (LCDs) from CMS MACs that list F84.2 as a covered diagnosis.
Showing top 10 of 40 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing F84.2.
1 Cigna
2 Medicare
4 Aetna
1 NY Medicaid
CPT Codes Commonly Billed with F84.2
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert F84.2 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| F84.2 | 3308 | 10000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To F84.2
Other codes in section F80-F89 (Pervasive and specific developmental disorders).
ICD-10 F84.2, Billing FAQ
Is ICD-10 code F84.2 billable? +
Yes, F84.2 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What codes are Type 1 Excludes for F84.2? +
Type 1 Excludes (never code together with F84.2): Asperger's syndrome (F84.5); Autistic disorder (F84.0); Other childhood disintegrative disorder (F84.3)
Is F84.2 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What ICD-9 codes does F84.2 map to? +
Per CMS GEMs, F84.2 maps to ICD-9 codes: 3308. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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