Stomatitis and related lesions (K12) ICD-10-CM
The K12 code range covers stomatitis and related lesions with 10 ICD-10-CM diagnosis codes. 8 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Use Additional Code
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
- code to identify:
- alcohol abuse and dependence F10
- exposure to environmental tobacco smoke Z77.22
- exposure to tobacco smoke in the perinatal period P96.81
- history of tobacco dependence Z87.891
- occupational exposure to environmental tobacco smoke Z57.31
- tobacco dependence F17
- tobacco use Z72.0
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Codes in the K12 Range 10 codes · 8 billable
- K12 Stomatitis and related lesionsNon-billable
- K12.0 Recurrent oral aphthae
- K12.1 Other forms of stomatitis
- K12.2 Cellulitis and abscess of mouth
- K12.3 Oral mucositis (ulcerative)Non-billable
- K12.30 Oral mucositis (ulcerative), unspecified
- K12.31 Oral mucositis (ulcerative) due to antineoplastic therapy
- K12.32 Oral mucositis (ulcerative) due to other drugs
- K12.33 Oral mucositis (ulcerative) due to radiation
- K12.39 Other oral mucositis (ulcerative)
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the K12 range.
Gingivitis, Necrotizing Ulcerative
An acute or chronic GINGIVITIS characterized by redness and swelling, NECROSIS extending from the interdental papillae along the gingival margins, PAIN; HEMORRHAGE, necrotic odor, and often a pseudomembrane. The condition may extend to the ORAL MUCOSA; TONGUE; PALATE; or PHARYNX. The etiology is somewhat unclear, but may involve a complex of FUSOBACTERIUM NUCLEATUM along with spirochetes BORRELIA or TREPONEMA.
Ludwig's Angina
Severe cellulitis of the submaxillary space with secondary involvement of the perimandibular spaces. It usually results from infection in the lower molar area or from an infection following a penetrating injury to the MOUTH FLOOR.
Mouth Floor
The area of the mouth beneath the TONGUE.
Noma
A severe gangrenous process occurring predominantly in debilitated and malnourished children, especially in underdeveloped countries. It typically begins as a small vesicle or ulcer on the gingiva that rapidly becomes necrotic and spreads to produce extensive destruction of the buccal and labial mucosa and tissues of the face, which may result in severe disfigurement and even death. Various bacteria have been implicated in the etiology. (Dorland, 27th ed)
Oral Fistula
An abnormal passage within the mouth communicating between two or more anatomical structures.
Stomatitis
INFLAMMATION of the soft tissues of the MOUTH, such as MUCOSA; PALATE; GINGIVA; and LIP.
Stomatitis, Aphthous
A recurrent disease of the oral mucosa of unknown etiology. It is characterized by small white ulcerative lesions, single or multiple, round or oval. Two to eight crops of lesions occur per year, lasting for 7 to 14 days and then heal without scarring. (From Jablonski's Dictionary of Dentistry, 1992, p742)
Stomatitis, Denture
Inflammation of the mouth due to denture irritation.
Stomatitis, Herpetic
Stomatitis caused by Herpesvirus hominis. It usually occurs as acute herpetic stomatitis (or gingivostomatitis), an oral manifestation of primary herpes simplex seen primarily in children and adolescents.
Vesicular Stomatitis
A viral disease caused by at least two distinct species (serotypes) in the VESICULOVIRUS genus: VESICULAR STOMATITIS INDIANA VIRUS and VESICULAR STOMATITIS NEW JERSEY VIRUS. It is characterized by vesicular eruptions on the ORAL MUCOSA in cattle, horses, pigs, and other animals. In humans, vesicular stomatitis causes an acute influenza-like illness.
Vesicular stomatitis Indiana virus
The type species of VESICULOVIRUS causing a disease symptomatically similar to FOOT-AND-MOUTH DISEASE in cattle, horses, and pigs. It may be transmitted to other species including humans, where it causes influenza-like symptoms.
Vesicular stomatitis New Jersey virus
A species of VESICULOVIRUS causing VESICULAR STOMATITIS primarily in cattle, horses, and pigs. It can be transmitted to humans where it causes influenza-like symptoms.
Vesiculovirus
A genus of the family RHABDOVIRIDAE that infects a wide range of vertebrates and invertebrates. The type species is VESICULAR STOMATITIS INDIANA VIRUS.
About the K12 Code Range
The ICD-10 code section K12 covers stomatitis and related lesions, including various inflammatory and ulcerative conditions affecting the mouth. These codes help specify diagnoses ranging from recurrent mouth ulcers to infectious or drug-induced oral mucositis and abscesses in oral soft tissues.
This section includes K12.0 for recurrent oral aphthae, also known as aphthous ulcers or canker sores, recognized by synonyms like Bednar's aphthae and minor oral aphthous ulceration. Code K12.1 groups other stomatitis types, such as contact stomatitis, denture-related irritation, and fungal infections like oral candidiasis. Codes K12.2 identify cellulitis and abscesses in the mouth and surrounding spaces, including Ludwig's angina and submandibular infections. The oral mucositis codes starting with K12.3 capture ulcerative mucosal inflammation, often due to cancer treatments (K12.31 for antineoplastic therapy, K12.32 for other drugs, and K12.33 for radiation). These detailed codes, such as "ICD-10 code for oral mucositis due to radiation," enable accurate recording of specific causes and presentations in mouth lesions, aiding precise documentation in healthcare.
Questions About This Page
How many billable codes are in the K12 range?
Of the 10 codes in this range, 8 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the K12 range classify?
The range classifies stomatitis and related lesions. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
