What are the ICD-10 and CPT (Current Procedural Terminology) codes for an established patient visiting an outpatient Primary Care Physician (PCP) with a canker sore?

ICD-10 and CPT Codes for Established Patient with Canker Sore

For an established patient presenting to an outpatient PCP with a canker sore, use ICD-10 code K12.0 (recurrent oral aphthae/recurrent aphthous stomatitis) and CPT code 99212,99213, or 99214 depending on the complexity of the evaluation and management service.

ICD-10 Diagnosis Code

• K12.0 is the appropriate ICD-10 code for recurrent aphthous stomatitis, which is the medical term for canker sores 1
• This code specifically captures "recurrent oral aphthae" and encompasses what patients commonly refer to as canker sores 1
• The diagnosis should be based on clinical characteristics of the oral ulcers, including their recurrent nature and typical morphology 1

CPT Procedure Codes

For established patient office visits, select from the following based on medical decision-making complexity:

• 99212: Straightforward medical decision-making (10 minutes)
• 99213: Low complexity medical decision-making (20 minutes)
• 99214: Moderate complexity medical decision-making (30 minutes)
• 99215: High complexity medical decision-making (40 minutes) - rarely needed for simple canker sore

Determining the Appropriate Level

• Use 99212 if the canker sore is simple, requires minimal evaluation, and straightforward management with over-the-counter recommendations
• Use 99213 if you need to assess for potential triggers (trauma, stress, food hypersensitivity), provide patient education, and prescribe topical treatments 1
• Use 99214 if the presentation requires evaluation for associated systemic disorders, hematinic deficiencies, gastrointestinal diseases, or if considering complex aphthosis variants 1

Clinical Considerations for Coding Accuracy

Evaluate for "correctable causes" that may affect coding complexity:

• Screen for hematinic deficiencies (iron, folate, B12) which can be associated with recurrent aphthous stomatitis 1
• Consider gastrointestinal diseases (celiac disease, inflammatory bowel disease) as potential underlying conditions 1
• Rule out Behçet's disease or complex aphthosis variants if presentation is atypical 1
• Document whether this is simple versus complex aphthosis, as this affects medical decision-making complexity 1

Documentation Requirements

Your documentation should include:

• Classification of the lesion morphology (minor aphthous ulcer, major aphthous ulcer, or herpetiform ulcer) 1
• Duration and frequency of recurrence 1
• Assessment of potential contributing factors (trauma, smoking, stress, hormonal state, family history, food hypersensitivity) 1
• Any associated systemic symptoms or conditions evaluated 1
• Treatment plan and patient education provided

Common Pitfalls to Avoid

• Do not confuse canker sores (aphthous stomatitis, K12.0) with herpes simplex lesions, which require different ICD-10 codes
• Avoid using unspecified stomatitis codes (K12.1 or K12.9) when the clinical presentation clearly indicates recurrent aphthous stomatitis 1
• Ensure the CPT code level matches the documented complexity of medical decision-making and time spent
• For established patients, the visit type must be coded as established (99212-99215), not new patient codes (99202-99205)