ICD-10-CM · Other

M26.02

M26.02 identifies underdevelopment of the maxilla (upper jaw) as a major anomaly of jaw size, classified under dentofacial anomalies in ICD-10-CM Chapter 13.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 16
Region: Other

Drawn from CDCICD10DataUnboundmedicineAAPCCMS

Documentation tips

What should appear in the chart to support M26.02.

Source · Editorial brief grounded in 5 cited references ↓

Specify 'maxillary hypoplasia' explicitly in the diagnosis — do not rely on symptom descriptions like 'midface deficiency' or 'class III malocclusion' alone, as those do not map to M26.02.
Distinguish whether the deficiency is transverse, vertical, or sagittal, and document whether it is congenital or acquired to support medical necessity for surgical or orthodontic intervention.
Record cephalometric or imaging findings (lateral cephalogram, CBCT) confirming skeletal maxillary deficiency — this supports both coding specificity and prior authorization.
If Robin's syndrome or acromegaly is the underlying cause, document that condition as the primary diagnosis — M26.02 is excluded in those scenarios per the tabular.
For surgical correction encounters, document the specific procedure planned or performed (e.g., Le Fort I osteotomy, distraction osteogenesis) to ensure CPT selection aligns with the diagnosis.

Related CPT procedures

Procedure codes commonly billed with M26.02. 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.

21199 $906.17

Segmental mandibular osteotomy with genioglossus muscle advancement — the lower jaw is cut in segments, repositioned, and the tongue-base muscle attachment is advanced forward.

21206 $873.43

Surgical reconstruction of the maxilla (upper jaw) via osteotomy — cutting and repositioning the bone to correct deformity from trauma, congenital defect, or disease.

21244 $897.48

Extraoral mandibular reconstruction using a transosteal bone plate — such as a mandibular staple bone plate — to restore structural integrity and function of the lower jaw.

21248 $1,023.40

Partial reconstruction of the mandible or maxilla using an endosteal implant (such as a blade or cylinder type) placed directly into the jawbone.

21249 $1,404.51

Complete reconstruction of the mandible or maxilla using an endosteal implant (blade or cylinder type) placed within the jawbone

Common coding pitfalls

The recurring mistakes coders make with M26.02 and adjacent codes.

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

Coding M26.02 when the provider documents mandibular hyperplasia (M26.03) as the cause of the class III relationship — the two can look clinically similar but require different codes.
Using M26.02 for unilateral condylar hypoplasia, which is explicitly excluded from M26.0 and belongs at M27.8.
Selecting M26.00 (unspecified anomaly of jaw size) when the documentation clearly states maxillary hypoplasia — M26.02 is the specific billable code and should be used when supported.
Failing to code Robin's syndrome (Q87.0) or acromegaly (E22.0) as the primary diagnosis when those conditions are documented as the etiology — the tabular excludes them from M26.0.
Omitting additional codes for associated malocclusion (M26.2x series) or jaw-cranial base relationship anomalies (M26.1x series) when those are also documented and clinically relevant.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M26.02 covers congenital or developmental maxillary hypoplasia — a condition in which the upper jaw is underdeveloped relative to normal anatomical proportions. This includes presentations documented as congenital maxillary hypoplasia, hypoplasia of the maxillary bone, and transverse maxillary hypoplasia. The condition commonly produces midface deficiency, class III skeletal malocclusion, nasal obstruction, and functional impairment of occlusion.

Use M26.02 when the provider specifically documents maxillary hypoplasia as the diagnosis. Do not confuse this with mandibular hyperplasia (M26.03), which can produce a clinically similar skeletal profile but originates from excess mandibular growth rather than maxillary deficiency. If the anomaly involves the mandible instead, use M26.04. For unilateral condylar hypoplasia, the tabular excludes that condition from this block — assign M27.8 instead.

M26.02 falls under parent code M26.0 (Major anomalies of jaw size), which itself excludes acromegaly (E22.0) and Robin's syndrome (Q87.0). If either of those underlies the jaw anomaly, code the underlying condition, not M26.02. This code groups into MS-DRG v43.0 categories 157–159 (Dental and oral diseases) and 011–013 (Tracheostomy for face, mouth, and neck diagnoses), relevant for inpatient billing scenarios involving surgical correction.

Sibling codes

Other billable codes under M26.0 (laterality / anatomic variants).

M26.01

Maxillary hyperplasia

M26.00

Unspecified anomaly of jaw size

M26.06

Microgenia

M26.03

Mandibular hyperplasia

M26.04

Mandibular hypoplasia

M26.07

Excessive tuberosity of jaw

M26.09

Other specified anomalies of jaw size

M26.05

Macrogenia

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01Is M26.02 valid for both congenital and acquired maxillary hypoplasia?

Yes. The approximate synonyms include both congenital maxillary hypoplasia and hypoplasia of the maxillary bone without restriction to etiology. Document whether the presentation is congenital or developmental to support medical necessity, but either maps to M26.02.

02How do I differentiate M26.02 from M26.03 on the claim?

M26.02 is maxillary hypoplasia (upper jaw underdevelopment); M26.03 is mandibular hyperplasia (lower jaw overgrowth). Both can produce a class III skeletal relationship. The provider must document which jaw is the anatomical source of the anomaly — coders cannot infer laterality of cause from the malocclusion pattern alone.

03Can I use M26.02 and M26.03 together on the same claim?

Yes, if the provider documents that both conditions coexist — maxillary deficiency combined with mandibular excess contributing to the overall skeletal discrepancy. Code both, sequenced according to the primary reason for the encounter.

04What is excluded from M26.02 that coders commonly miss?

Unilateral condylar hypoplasia is excluded from M26.0 entirely and maps to M27.8. Robin's syndrome (Q87.0) and acromegaly (E22.0) are also excluded — when those are the underlying diagnosis, do not assign M26.02.

05Which MS-DRGs does M26.02 map to for inpatient claims?

M26.02 groups to MS-DRG v43.0 DRGs 157–159 (Dental and oral diseases, with/without CC/MCC) and DRGs 011–013 (Tracheostomy for face, mouth, and neck diagnoses), depending on the presence of complications or comorbidities.

06Does M26.02 require a 7th character extension?

No. M-codes in Chapter 13 do not use 7th-character extensions unless specifically indicated in the tabular (such as M48.4/M48.5 or M80/M84 fracture codes). M26.02 is a 5-character code and is complete as coded.

07What CPT codes are typically associated with surgical correction of maxillary hypoplasia?

Le Fort I osteotomy procedures (CPT 21141–21160 range) are the most common surgical corrections. Distraction osteogenesis device placement (21244, 21248, 21249) may also apply depending on the surgical approach documented by the provider.

Sources & references

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

Mira AI Scribe

Mira AI Scribe captures the provider's documented diagnosis of maxillary hypoplasia, including the characterization (congenital, transverse, or sagittal), associated cephalometric or CBCT findings confirming skeletal deficiency, and any notation of underlying syndromes or conditions. This prevents assignment of the nonspecific M26.00 or misrouting to mandibular codes, and flags when an excluding condition like Robin's syndrome requires a different primary diagnosis.

See how Mira captures M26.02 documentation