2026 ICD-10-CM Diagnosis Code Q04.1Arhinencephaly

ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q04

ICD-10-CM Q04.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Q04.1 is a billable ICD-10-CM diagnosis code for arhinencephaly. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is exempt from POA reporting. Coders also document this condition as congenital anosmia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.

Code Identity

ICD-10-CM Code
Q04.1
Billable Status
Yes — Valid for Submission
Code Describes
Arhinencephaly
Short Description
Arhinencephaly
Same as the full description in the CMS dataset.
Parent Code
Q04
Other congenital malformations of brain

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ00-Q07Congenital malformations of the nervous system
CategoryQ04Other congenital malformations of brain
This CodeQ04.1Arhinencephaly

Present on Admission (POA)Billing

Q04.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Congenital anosmia
  • Disorder of smell
  • Isolated arhinencephaly
  • Loss of sense of smell

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Arhinencephaly

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL004
Nervous system congenital anomalies
Default principal diagnosis: inpatient Yes · outpatient Yes

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 Q04.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
742.2 Reduction deform, brain
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Q04.1Overview

Is Q04.1 (Other congenital malformations of brain) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report arhinencephaly on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is Q04.1 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 arhinencephaly on inpatient claims.

What is the ICD-9 equivalent of Q04.1?

Under the General Equivalence Mappings, arhinencephaly converts to ICD-9-CM 742.2 (reduction deform, brain). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.