ICD-10-CM · Other

M27.8

M27.8 classifies documented jaw diseases that are named and identifiable but do not map to any more specific code within the M27 category — including cherubism, exostosis, fibrous dysplasia, unilateral condylar hyperplasia, and unilateral condylar hypoplasia.

Verified May 8, 2026 · 5 sources ↓

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

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M27.8.

Source · Editorial brief grounded in 5 cited references ↓

Name the specific jaw condition in the note (e.g., 'fibrous dysplasia of mandible,' 'unilateral condylar hyperplasia, right side') — 'other jaw disease' alone is not sufficient to distinguish M27.8 from M27.9.
Record imaging findings that support the diagnosis: CT or panoramic radiograph findings, bone scan results, or MRI characteristics should be referenced by date and result.
Document laterality when applicable — unilateral condylar hyperplasia and hypoplasia are inherently side-specific, and the operative note or clinical record should name the affected side.
If cherubism is the diagnosis, document family history when present, as this is a hereditary fibrous condition — this supports medical necessity and distinguishes it from other fibro-osseous lesions.
For exostosis of the jaw, document the anatomic location (buccal, lingual, palatal torus) and clinical rationale for treatment, particularly if surgical excision is planned.

Related CPT procedures

Procedure codes commonly billed with M27.8. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

21044 $764.88

Open surgical excision of a malignant tumor from the mandible (lower jaw bone), performed via intraoral or extraoral approach.

21045 $1,061.15

Surgical removal or resection of the mandible involving extensive bone and soft tissue work, typically indicated for aggressive tumors, severe infection, or significant traumatic defect requiring wide-field operative exposure.

21046 $899.49

Excision of a benign tumor or cyst of the mandible requiring an intra-oral osteotomy, used for locally aggressive or destructive lesions that cannot be managed by simple enucleation or curettage alone.

21047 $1,076.51

Excision of a benign cyst or tumor of the mandible (lower jaw) using an extraoral approach with osteotomy and partial mandibulectomy, including repair.

21048 $906.83

Surgical removal of a benign cyst or tumor from the maxilla (upper jaw) via an intraoral approach that requires cutting through bone (osteotomy) — used for locally aggressive or destructive lesions.

21049 $1,021.07

Excision of a benign tumor or cyst of the maxilla requiring extra-oral osteotomy and partial maxillectomy — used for locally aggressive or destructive lesions.

21193 $1,108.58

Surgical reconstruction of the mandibular rami (vertical portions of the lower jaw) to correct deformity or dysfunction without the use of bone or tissue grafting material.

21194 $1,279.59

Reconstruction of the mandibular rami using a horizontal, vertical, C, or L osteotomy, with bone graft harvested from the patient (graft procurement included).

21195 $1,217.46

Surgical reconstruction of the mandibular rami and/or body using a sagittal split osteotomy technique, performed without internal rigid fixation hardware.

21196 $1,296.62

Surgical reconstruction of the mandibular body and/or rami using a sagittal split osteotomy technique, with internal fixation applied to stabilize the repositioned jaw segments.

21240 $943.58

Arthroplasty of the temporomandibular joint using autogenous graft material harvested from the patient, performed to restore jaw function.

21242 $923.20

Arthroplasty of the temporomandibular joint using allograft (donor) tissue to repair, reposition, or reconstruct joint components.

21243 $1,456.28

Arthroplasty of the temporomandibular joint using a prosthetic joint replacement device

70486 View procedure details

70487 View procedure details

70488 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M27.8 and adjacent codes.

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

Using M27.9 (unspecified) when the provider has actually named the condition — if the diagnosis is documented as fibrous dysplasia or cherubism, M27.8 is required; M27.9 is not a valid fallback for a named condition.
Confusing jaw exostosis (M27.8) with exostosis at other musculoskeletal sites — exostosis coded here is specific to the jaw; use the appropriate site-specific code for non-jaw exostoses.
Assigning M27.8 for jaw conditions that have their own dedicated codes — inflammatory jaw conditions belong in M27.2, alveolitis in M27.3, and giant cell granuloma in M27.1; always check sibling codes before landing on M27.8.
Applying M27.8 to congenital jaw deformities that should be coded from the Q chapter — M27.8 is for acquired or disease-process conditions; congenital malformations of the jaw may require Q-chapter codes instead.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M27.8 is the correct code when the provider documents a specific jaw condition that has no dedicated ICD-10-CM code of its own. The Tabular List explicitly includes cherubism, exostosis, fibrous dysplasia, unilateral condylar hyperplasia, and unilateral condylar hypoplasia under this code — so if the note names any of these, M27.8 is the right selection, not M27.9 (unspecified) or a broader musculoskeletal catch-all.

This code sits within the M27 parent category ('Other diseases of jaws'), which also contains M27.0 (developmental disorders), M27.1 (giant cell granuloma, central), M27.2 (inflammatory conditions), and M27.3 (alveolitis). Before assigning M27.8, verify the condition does not map to one of these sibling codes. M27.9 is reserved for jaw disease where the specific type is genuinely unknown or undocumented — never use it when the diagnosis is named.

M27.8 appears in CMS coverage determinations alongside other jaw codes, including in the context of amniotic and placental-derived product billing policies, indicating it does surface in payer LCD/NCD contexts. Always confirm the payer's coverage criteria when billing for surgical or regenerative procedures tied to this diagnosis.

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

Source · CDC ICD-10-CM Official Tabular List · 2026

Includes

Cherubism
Exostosis
Fibrous dysplasia
Unilateral condylar hyperplasia
Unilateral condylar hypoplasia

Excludes 1 — never code together

jaw pain (R68.84)

Sibling codes

Other billable codes under M27 (laterality / anatomic variants).

M27.3

Alveolitis of jaws

M27.1

Giant cell granuloma, central

M27.9

Disease of jaws, unspecified

M27.0

Developmental disorders of jaws

M27.2

Inflammatory conditions of jaws

Frequently asked questions

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

01What conditions are explicitly included under M27.8?

The ICD-10-CM Tabular List includes cherubism, exostosis, fibrous dysplasia, unilateral condylar hyperplasia, and unilateral condylar hypoplasia as 'Applicable To' entries under M27.8. If the provider documents any of these by name, M27.8 is the correct code.

02When should I use M27.9 instead of M27.8?

Use M27.9 only when the provider documents jaw disease without specifying what type it is. If the condition is named — even if it lacks its own dedicated code — M27.8 is correct. M27.9 is a true 'unknown' code, not a default.

03Can M27.8 be used for both the mandible and maxilla?

Yes. M27.8 is not restricted to one jaw — it applies to diseases of either the mandible or maxilla. Document the specific anatomic site in the clinical record even though the code does not distinguish between them.

04Is M27.8 appropriate for jaw conditions that are congenital in origin?

It depends on classification intent. Some conditions listed under M27.8 (like cherubism) have a hereditary basis but are classified here, not in the Q chapter. For other congenital jaw malformations not listed in M27.8's 'Applicable To,' verify whether a Q-chapter code is more appropriate by checking the Alphabetic Index.

05Does M27.8 require a 7th character?

No. M27.8 is a complete, billable 5-character code with no 7th-character extension required. It does not use the A/D/S encounter extension convention that applies to injury S-codes.

06How does M27.8 interact with surgical procedure coding for jaw conditions?

M27.8 serves as the supporting diagnosis for jaw surgeries such as excision of exostosis or treatment of fibrous dysplasia. Pair it with the appropriate CPT procedure code and confirm payer LCD requirements — M27.8 appears in CMS billing and coding articles and may be subject to specific coverage criteria depending on the procedure.

07Can M27.8 be reported on the same claim as TMJ disorder codes?

Potentially yes, if both conditions are documented and treated. TMJ disorders have their own codes (e.g., M26.60–M26.69). There is no Excludes note prohibiting concurrent coding, but each condition must be independently documented and clinically distinct.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 (FY2026, effective October 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M26-M27/M27-/M27.8
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M27.8
04
cms.gov
https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=58865&ver=19
05
cms.gov
https://www.cms.gov/Medicare/Coding/ICD10/Downloads/2019-ICD10-Coding-Guidelines-.pdf

Mira AI Scribe

Mira's AI scribe captures the named jaw condition (e.g., fibrous dysplasia, unilateral condylar hyperplasia, cherubism, exostosis), the affected side when laterality is clinically relevant, supporting imaging type and key findings, and any prior conservative or surgical treatment history. That specificity prevents a downcode to M27.9 (unspecified) and ensures the claim reflects the documented diagnosis — not a generic jaw disease placeholder.

See how Mira captures M27.8 documentation