M26.06 identifies microgenia — an abnormally small or underdeveloped chin (symphysis menti region of the mandible) classified as a major anomaly of jaw size under the dentofacial anomalies category.

Documentation tips

What should appear in the chart to support M26.06.

Source · Editorial brief grounded in 4 cited references ↓

• Document 'microgenia' explicitly — vague terms like 'small chin' or 'chin deficiency' may not map cleanly to M26.06 on audit.
• Distinguish microgenia (chin region only) from mandibular hypoplasia (M26.04, affecting the whole mandible) in the clinical note; conflating the two can result in the wrong code.
• Record any associated dentofacial anomalies separately (e.g., malocclusion, jaw asymmetry) so each condition can be coded with its own specific code.
• If surgical planning is the purpose of the visit, document how microgenia specifically contributes to the functional or structural problem justifying the procedure.
• Rule out and explicitly exclude Robin syndrome (Q87.0) or acromegaly (E22.0) in the note when those diagnoses are in the differential — payers may flag co-reporting of these Excludes1 conditions.

Related CPT procedures

Procedure codes commonly billed with M26.06. 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 M26.06 and adjacent codes.

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

• Assigning M26.06 when Robin syndrome (Q87.0) is the underlying diagnosis — Q87.0 is an Excludes1 condition at the M26.0 category level, making simultaneous use of both codes a coding violation.
• Confusing M26.06 (microgenia, chin-specific) with M26.04 (mandibular hypoplasia, whole mandible) — these are clinically and structurally distinct; the provider's documented term controls the code selection.
• Using parent code M26.04 or M26.00 when the documentation clearly states microgenia — M26.06 is billable and specific; dropping to an unspecified code is unnecessary and may trigger a query.
• Omitting secondary dentofacial anomaly codes (e.g., malocclusion M26.2x) when they are documented — microgenia frequently coexists with other jaw-size or occlusal anomalies that should each be reported.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Sibling codes

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