| K12 | Stomatitis and related lesions | NON-BILLABLE CODE |
| K12.0 | Recurrent oral aphthae | BILLABLE CODE |
| K12.1 | Other forms of stomatitis | BILLABLE CODE |
| K12.2 | Cellulitis and abscess of mouth | BILLABLE CODE |
| K12.3 | Oral mucositis (ulcerative) | NON-BILLABLE CODE |
| K12.30 | Oral mucositis (ulcerative), unspecified | BILLABLE CODE |
| K12.31 | Oral mucositis (ulcerative) due to antineoplastic therapy | BILLABLE CODE |
| K12.32 | Oral mucositis (ulcerative) due to other drugs | BILLABLE CODE |
| K12.33 | Oral mucositis (ulcerative) due to radiation | BILLABLE CODE |
