M27.49 classifies jaw cysts that fall outside the unspecified category — specifically aneurysmal, hemorrhagic, and traumatic cysts of the jaw bone — as distinct from odontogenic cysts coded elsewhere under K09.

Documentation tips

What should appear in the chart to support M27.49.

Source · Editorial brief grounded in 5 cited references ↓

• Name the cyst type explicitly — 'traumatic bone cyst,' 'aneurysmal cyst,' or 'hemorrhagic cyst' — in the operative or pathology report to justify M27.49 over the unspecified M27.40.
• Record imaging findings (panoramic radiograph, CT, or CBCT) that characterize the lesion: unilocular vs. multilocular, cortical expansion, internal septation — these support medical necessity and distinguish cyst types.
• Document whether the cyst involves the mandible or maxilla and note the involved anatomic region (anterior, posterior, ramus) — while M27.49 has no laterality subcode, payer prior auth and operative reports benefit from this specificity.
• If a pathology specimen is submitted, reference the oral pathology report in the clinical note; a histopathologic diagnosis of 'traumatic bone cyst' or 'aneurysmal bone cyst' is the gold-standard documentation anchor for M27.49.
• Confirm the cyst is a bone cyst of the jaw — not an oral soft-tissue cyst — before assigning M27.49; soft-tissue lesions of the oral region route to K09.-.

Related CPT procedures

Procedure codes commonly billed with M27.49. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

Common coding pitfalls

The recurring mistakes coders make with M27.49 and adjacent codes.

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

• Coding M27.49 for odontogenic cysts (dentigerous, gingival, lateral periodontal) — those belong under K09.0 or K09.-, not M27.49; the Excludes1 at M27.4 is a hard exclusion.
• Using M27.49 when the operative or pathology report only says 'jaw cyst' without specifying type — default to M27.40 (Unspecified cyst of jaw) unless a named cyst type is documented.
• Confusing traumatic bone cyst of the jaw with a radicular (periapical) cyst — radicular cysts route to M27.2, not M27.49.
• Assigning M27.0 (Developmental disorders of jaws) for a Stafne's cyst or latent bone cyst when M27.49 appears tempting — M27.0 is the correct code for those entities; they are explicitly excluded from M27.4.
• Missing the K09.- Excludes1 fence and coding M27.49 alongside a K09 code for the same lesion — only one jaw-cyst code should be assigned for a single lesion unless documented as separate, distinct pathologies.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

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

Sibling codes

Other billable codes under M27.4 (laterality / anatomic variants).