ICD-10-CM · Other

M26.11

M26.11 classifies documented asymmetry of the maxilla as an anomaly of the jaw-cranial base relationship, distinct from generalized jaw size anomalies or mandibular asymmetry.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 14
Region: Other

Drawn from CDCICD10DataAAPCNIH

Documentation tips

What should appear in the chart to support M26.11.

Source · Editorial brief grounded in 4 cited references ↓

Specify 'maxillary asymmetry' by name in the assessment — vague terms like 'facial asymmetry' or 'jaw asymmetry' won't support M26.11 and may force a drop to M26.10 or M26.12.
Document the imaging modality that confirms the finding (CBCT, cephalometric radiograph, panoramic X-ray) and the specific measurement or visual finding supporting asymmetry.
If both asymmetry and size anomaly are present (e.g., maxillary asymmetry with hemimaxillary hyperplasia), document each finding separately to support dual coding with M26.01 or M26.02.
Record whether the asymmetry is congenital or acquired/developmental, as this affects clinical justification for surgical authorization and payer medical necessity review.
For orthognathic surgery cases, include the orthodontist or oral surgeon's treatment plan documenting the maxillary asymmetry as the surgical indication.

Related CPT procedures

Procedure codes commonly billed with M26.11. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

21141 $1,208.44

Midface reconstruction via LeFort I osteotomy, single-piece maxillary segment moved in any direction, performed without bone graft.

21142 $1,238.17

LeFort I midface reconstruction performed in two separate maxillary segments, repositioning the upper jaw in any direction, without bone grafting.

21143 $1,273.58

LeFort I osteotomy of the maxilla performed in three or more bone segments, without bone grafting, for midface reconstruction.

21145 $1,390.81

LeFort I single-piece maxillary osteotomy performed with bone grafting to reposition the upper jaw and correct midface skeletal deformity.

21146 $1,452.94

LeFort I midface reconstruction split into two segments, moved in any direction, with bone grafts obtained at the same operative session — the classic approach for ungrafted unilateral alveolar clefts.

21147 $1,525.42

LeFort I osteotomy with segmentation into three or more pieces, repositioned in any direction, with bone grafting including autograft harvest

21150 $1,415.20

Reconstruction of the midface via a modified Le Fort II osteotomy pattern that advances the nasal-orbital complex anteriorly without mobilizing the zygoma.

21151 $1,553.81

Midface reconstruction via LeFort II osteotomy, movement in any direction, with bone grafting including autograft harvest

21154 $1,673.72

Extracranial LeFort III midface reconstruction requiring bone grafts, performed without a simultaneous LeFort I osteotomy.

21155 $1,851.41

Reconstruction of the midface using a modified LeFort III osteotomy with internal fixation, repositioning the midface skeleton to correct severe craniofacial deformities.

21160 $2,392.84

Reconstruction of the midface (Le Fort III level) with advancement using an internal distraction device — a high-complexity craniofacial procedure performed for severe midface hypoplasia or retrusion.

70486 View procedure details

70487 View procedure details

70488 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M26.11 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Using M26.12 (Other jaw asymmetry) when documentation clearly specifies the maxilla — M26.11 is the correct specific code and should not be bypassed.
Defaulting to M26.10 (Unspecified anomaly of jaw-cranial base relationship) when the provider has documented maxillary asymmetry — M26.10 is a fallback, not a synonym.
Conflating maxillary asymmetry with maxillary size anomalies: M26.01 (hyperplasia) and M26.02 (hypoplasia) are separate codes under M26.0 and are not interchangeable with M26.11.
Omitting M26.11 from the claim when it is a surgical indication — this can weaken medical necessity support for orthognathic procedure codes billed on the same claim.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

M26.11 applies when the maxilla is structurally asymmetric relative to the cranial base — a finding documented in orthognathic surgery workups, orthodontic evaluations, and oral/maxillofacial surgical planning. The asymmetry may be congenital or developmental, and is typically confirmed through cephalometric radiographs, CBCT imaging, or clinical facial analysis. Use this code when the provider explicitly identifies the maxilla as the asymmetric structure; do not use it as a catch-all for facial asymmetry.

This code sits under parent M26.1 (Anomalies of jaw-cranial base relationship). Its nearest neighbors are M26.10 (unspecified jaw-cranial base anomaly) and M26.12 (other jaw asymmetry — use for mandibular or combined jaw asymmetry not attributable solely to the maxilla). If the asymmetry involves maxillary size excess or deficiency, also consider whether M26.01 (maxillary hyperplasia) or M26.02 (maxillary hypoplasia) captures the primary finding more accurately — asymmetry and size anomaly can coexist and may require both codes.

M26.11 groups into MS-DRGs 157–159 (Dental and Oral Diseases) and 011–013 (Tracheostomy for face, mouth and neck diagnoses) depending on the procedure and complication level. It is commonly paired with orthognathic surgery CPT codes and pre-surgical orthodontic evaluation visits.

Sibling codes

Other billable codes under M26.1 (laterality / anatomic variants).

M26.19

Other specified anomalies of jaw-cranial base relationship

M26.10

Unspecified anomaly of jaw-cranial base relationship

M26.12

Other jaw asymmetry

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 4 cited references ↓

01What is the difference between M26.11 and M26.12?

M26.11 is specific to the maxilla. M26.12 (Other jaw asymmetry) covers asymmetry of other jaw structures, most commonly the mandible, or combined jaw asymmetry not solely attributable to the maxilla. Use M26.11 only when the provider documents the maxilla as the asymmetric structure.

02Can M26.11 and M26.01 or M26.02 be coded together?

Yes. Maxillary asymmetry (M26.11) and maxillary hyperplasia (M26.01) or hypoplasia (M26.02) are in different subcategories and can coexist. Code both when documentation supports both findings — for example, hemimaxillary hyperplasia causing facial asymmetry.

03Does M26.11 require a 7th character?

No. M26.11 is a 5-character code with no 7th-character extension requirement. It is complete and billable as listed.

04Which MS-DRGs does M26.11 map to?

M26.11 maps to MS-DRG 157–159 (Dental and Oral Diseases, with/without CC/MCC) and MS-DRG 011–013 (Tracheostomy for face, mouth and neck diagnoses) per MS-DRG v43.0. The assigned DRG depends on the principal procedure and complication/comorbidity level.

05Is M26.11 appropriate for orthodontic-only visits, or only for surgical cases?

M26.11 is appropriate for any encounter where maxillary asymmetry is the documented diagnosis — including orthodontic evaluation, pre-surgical planning, and post-surgical follow-up. Surgical intent is not required to use the code.

06When should I use M26.10 instead of M26.11?

Use M26.10 (Unspecified anomaly of jaw-cranial base relationship) only when documentation describes a jaw-cranial base anomaly but does not specify the structure or type. If the maxilla is named, M26.11 is required — M26.10 should not be used as a default when more specific information is available.

07Are there any Excludes1 or Excludes2 notes affecting M26.11?

No Excludes1 or Excludes2 notes are directly attached to M26.11. Review the parent category M26 and chapter-level guidelines for any applicable exclusions when coding complex craniofacial or congenital anomaly cases alongside M26.11.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M26-M27/M26-/M26.11
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M26.11
04
vsac.nlm.nih.gov
https://vsac.nlm.nih.gov/context/cs/codesystem/ICD10CM/version/2023/code/M26.11/info

Mira AI Scribe

The Mira AI Scribe captures the provider's explicit identification of maxillary asymmetry, the imaging study confirming it (CBCT or cephalometric analysis), severity descriptors, and whether it is congenital or developmental in origin. Capturing this specificity prevents a downcode to M26.10 (unspecified) or miscoding to M26.12 (other jaw asymmetry), both of which can trigger payer requests for additional documentation on orthognathic surgery claims.

See how Mira captures M26.11 documentation