Actinomycosis (A42) ICD-10-CM
The A42 code range covers actinomycosis 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.
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.
- actinomycetoma B47.1
Codes in the A42 Range 10 codes · 8 billable
- A42 ActinomycosisNon-billable
- A42.0 Pulmonary actinomycosis
- A42.1 Abdominal actinomycosis
- A42.2 Cervicofacial actinomycosis
- A42.7 Actinomycotic sepsis
- A42.8 Other forms of actinomycosisNon-billable
- A42.81 Actinomycotic meningitis
- A42.82 Actinomycotic encephalitis
- A42.89 Other forms of actinomycosis
- A42.9 Actinomycosis, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the A42 range.
Actinomyces
A genus of gram-positive, rod-shaped bacteria whose organisms are nonmotile. Filaments that may be present in certain species are either straight or wavy and may have swollen or clubbed heads.
Actinomycosis
Infections with bacteria of the genus ACTINOMYCES.
Actinomycosis, Cervicofacial
A form of ACTINOMYCOSIS characterized by slow-growing inflammatory lesions of the lymph nodes that drain the mouth (lumpy jaw), reddening of the overlying skin, and intraperitoneal abscesses.
Typhlitis
Necrotizing inflammation of the CECUM (typhlon in Greek), sometimes spreading to the APPENDIX and/or the ILEUM. Symptoms include ABDOMINAL PAIN and DIARRHEA. Its pathogenesis is multifactorial. Typhlitis is often associated with NEUTROPENIA and chemotherapy in immunocompromised individuals (IMMUNOCOMPROMISED HOST).
About the A42 Code Range
ICD-10 code A42 and its subcodes identify different forms of actinomycosis, a rare bacterial infection caused primarily by Actinomyces species. These codes cover infections in various body parts including the lungs, abdomen, face and neck, central nervous system, and cases of sepsis related to this condition.
These codes help healthcare professionals precisely classify actinomycosis cases by location and severity. For example, A42.0 refers to pulmonary actinomycosis, also known as actinomycotic pneumonia or pneumonia caused by anaerobic bacteria. A42.1 is used for abdominal infections like actinomycotic colitis or hepatic actinomycosis. The cervicofacial form, including mandibular or submandibular infections, falls under A42.2. More serious systemic involvement such as actinomycotic sepsis or meningitis is coded as A42.7 and A42.81, respectively. The unspecified code A42.9 applies when the infection site is not clearly documented. Knowing these distinctions aids in accurate diagnosis, treatment planning, and billing for infections linked to Actinomyces bacteria.
Questions About This Page
How many billable codes are in the A42 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 A42 range classify?
The range classifies actinomycosis. 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.
