2027 ICD-10-CM Diagnosis Code Q04.0Congenital malformations of corpus callosum
ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q04
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 182
- POA Exempt
- Chronic Condition
Q04.0 is a billable ICD-10-CM diagnosis code for congenital malformations of corpus callosum. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 14 closely related codes. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.
For Medicare Advantage risk adjustment, Q04.0 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q04.0 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the nervous system (Q00-Q07).
Medicare Risk Adjustment (HCC)Billing
Q04.0 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acrocallosal syndrome
- Agenesis of corpus callosum
- Agenesis of corpus callosum and abnormal genitalia syndrome
- Agenesis of corpus callosum with lipoma
- Agenesis of corpus callosum, intellectual disability, coloboma, micrognathia syndrome
- Agenesis of corpus callosum, macrocephaly, hypertelorism syndrome
- Andermann syndrome
- Aplasia of corpus callosum
- Atrophy of corpus callosum
- Congenital coloboma of iris
- Congenital hypoplasia of cerebral hemisphere
- Congenital hypoplasia of cerebral white matter
- Congenital malformation of corpus callosum
- Disorder of serine metabolism
- Hypoplasia of corpus callosum
- Infantile osteopetrosis with neuroaxonal dysplasia syndrome
- Intellectual disability, hypoplastic corpus callosum, preauricular tag syndrome
- L1 syndrome
- Mass of preauricular region
- Microcephaly, corpus callosum and cerebellar vermis hypoplasia, facial dysmorphism, intellectual disability syndrome
- Microcephaly, corpus callosum hypoplasia, intellectual disability, facial dysmorphism syndrome
- Microcephaly, polymicrogyria, corpus callosum agenesis syndrome
- Microcephaly, thin corpus callosum, intellectual disability syndrome
- Partial agenesis of corpus callosum
- Partial corpus callosum agenesis, cerebellar vermis hypoplasia with posterior fossa cysts syndrome
- Severe intellectual disability, agenesis of corpus callosum, facial dysmorphism, cerebellar ataxia syndrome
- Spastic tetraplegia, thin corpus callosum, progressive postnatal microcephaly syndrome
- Temtamy syndrome
- White matter hypoplasia, corpus callosum agenesis, intellectual disability syndrome
- X-linked complicated corpus callosum dysgenesis
- X-linked lissencephaly with abnormal genitalia syndrome
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q04.0: its own notes plus those printed at Q04 and Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Agenesis of corpus callosum
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Q04.0, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
corpus callosum Q04.0
Aplasia See Also: Agenesis;
corpus callosum Q04.0
Malformation (congenital) See Also: Anomaly;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Brain Malformations
Most brain malformations begin long before a baby is born. Something damages the developing nervous system or causes it to develop abnormally. Sometimes it's a genetic problem. In other cases, exposure to certain medicines, infections, or radiation during pregnancy interferes with brain development.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q04.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q04.0Overview
What is the ICD-10 code for congenital malformations of corpus callosum?
The ICD-10-CM code for congenital malformations of corpus callosum is Q04.0 (sometimes written as Q040). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q04.0 (Other congenital malformations of brain) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report congenital malformations of corpus callosum on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q04.0 group to?
When congenital malformations of corpus callosum is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 91, 92, 93, with relative weights from 0.7783 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q04.0 a CC or MCC?
CMS lists Q04.0 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 14 closely related codes in its exclusion list.
Is Q04.0 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for congenital malformations of corpus callosum on inpatient claims. The code appears in the Congenital malformations of the nervous system (Q00-Q07) range of the CMS exempt list.
What HCC is Q04.0?
Q04.0 (congenital malformations of corpus callosum) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 155.
Does Q04.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, Q04.0 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.
