ICD-10-CM Code For Actinomycosis: Group Overview

The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code group A42 includes diagnoses for actinomycosis, chronic bacterial infections caused by Actinomyces species that can involve cervicofacial, thoracic, abdominal, or other anatomic sites. These ICD-10-CM diagnosis codes are used to document disease location, extent of local invasion or abscess formation, and complications such as sinus tracts or dissemination. Accurate coding within the ICD-10-CM A42 group supports proper claim adjudication, complete clinical documentation, and appropriate reimbursement.

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ICD-10-CM A42: Actinomycosis Overview

The ICD-10-CM A42 code group captures actinomycosis infections caused by Actinomyces species affecting various body sites, including cervicofacial, thoracic, and abdominal regions. These are chronic bacterial infections characterized by abscesses, sinus tract formation, and sulfur granules. Accurate coding matters for capturing disease complexity, documenting extent of organ involvement, and supporting appropriate reimbursement and resource allocation.

When to Use

Use a code from this group when clinical documentation confirms actinomycosis and specifies the infected anatomic site and relevant complications. Select the most specific code available to reflect location, severity, and presence of abscesses or sinus tract formation.

ICD-10-CM Codes

8 rows

ICD-10-CM Code	Description
A42.0	Pulmonary actinomycosis
A42.1	Abdominal actinomycosis
A42.2	Cervicofacial actinomycosis
A42.7	Actinomycotic sepsis
A42.81	Actinomycotic meningitis
A42.82	Actinomycotic encephalitis
A42.89	Other forms of actinomycosis
A42.9	Actinomycosis, unspecified

DRG Codes

19 rows

DRG Code	Description
177	Respiratory Infections and Inflammations with MCC
178	Respiratory Infections and Inflammations with CC
179	Respiratory Infections and Inflammations without CC/MCC
371	Major Gastrointestinal Disorders and Peritoneal Infections with MCC
372	Major Gastrointestinal Disorders and Peritoneal Infections with CC
373	Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCC
606	Minor Skin Disorders with MCC
607	Minor Skin Disorders without MCC
791	Prematurity with Major Problems
793	Full Term Neonate with Major Problems
867	Other Infectious and Parasitic Diseases Diagnoses with MCC
868	Other Infectious and Parasitic Diseases Diagnoses with CC
869	Other Infectious and Parasitic Diseases Diagnoses without CC/MCC
870	Septicemia or Severe Sepsis with MV >96 Hours
871	Septicemia or Severe Sepsis without MV >96 Hours with MCC
872	Septicemia or Severe Sepsis without MV >96 Hours without MCC
974	HIV with Major Related Condition with MCC
975	HIV with Major Related Condition with CC
976	HIV with Major Related Condition without CC/MCC

Typical Clinical Scenarios

An adult presents to the emergency department with acute onset of fever, severe jaw pain, swelling of the mandibular region, and a draining sinus tract after recent dental extraction. Examination and imaging show a localized cervicofacial abscess with sulfur granules on culture consistent with Actinomyces species; the clinician assigns a diagnosis from this group for acute cervicofacial actinomycosis. Typical codes: A42.0
A middle-aged patient with a history of prior chest surgery develops persistent cough, weight loss, and a chronic pulmonary consolidation on chest CT; bronchoscopy yields filamentous gram-positive bacteria consistent with actinomycosis causing thoracic involvement. Because the infection involves lung tissue with chronic symptoms and radiographic mass-like lesions, a thoracic actinomycosis code from this group is assigned. Typical codes: A42.1
A patient with poorly controlled diabetes presents for follow-up after recent abdominal surgery and now has a non-healing postoperative abdominal wall sinus and intra-abdominal abscess; cultures identify Actinomyces species contributing to an intra-abdominal/pelvic infection as a complication of the operative course. The diagnosis from this group is used to capture intra-abdominal actinomycosis as a postoperative complication/comorbidity affecting recovery. Typical codes: A42.2, A42.7

Related Codes

A30-LEPROSY-HANSEN-S-DISEASE

ICD-10-CM Code For Leprosy Hansen's Disease: Group Overview

A31-INFECTION-DUE-TO-OTHER-MYCOBACTERIA

ICD-10-CM Code For Infection Due To Other Mycobacteria: Group Overview

A32-LISTERIOSIS

ICD-10-CM Code For Listeriosis: Group Overview

A33-TETANUS-NEONATORUM

ICD-10-CM Code For Tetanus Neonatorum: Group Overview

A34-OBSTETRICAL-TETANUS

ICD-10-CM Code For Obstetrical Tetanus: Group Overview

A35-OTHER-TETANUS

ICD-10-CM Code For Other Tetanus: Group Overview

A36-DIPHTHERIA

ICD-10-CM Code For Diphtheria: Group Overview

A37-WHOOPING-COUGH

ICD-10-CM Code For Whooping Cough: Group Overview

A38-SCARLET-FEVER

ICD-10-CM Code For Scarlet Fever: Group Overview

A39-MENINGOCOCCAL-INFECTION

ICD-10-CM Code For Meningococcal Infection: Group Overview

Showing 1–10 of 16

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

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When to Use

ICD-10-CM Codes

8 rows

ICD-10-CM Code	Description
A42.0	Pulmonary actinomycosis
A42.1	Abdominal actinomycosis
A42.2	Cervicofacial actinomycosis
A42.7	Actinomycotic sepsis
A42.81	Actinomycotic meningitis
A42.82	Actinomycotic encephalitis
A42.89	Other forms of actinomycosis
A42.9	Actinomycosis, unspecified

DRG Codes

19 rows

DRG Code	Description
177	Respiratory Infections and Inflammations with MCC
178	Respiratory Infections and Inflammations with CC
179	Respiratory Infections and Inflammations without CC/MCC
371	Major Gastrointestinal Disorders and Peritoneal Infections with MCC
372	Major Gastrointestinal Disorders and Peritoneal Infections with CC
373	Major Gastrointestinal Disorders and Peritoneal Infections without CC/MCC
606	Minor Skin Disorders with MCC
607	Minor Skin Disorders without MCC
791	Prematurity with Major Problems
793	Full Term Neonate with Major Problems
867	Other Infectious and Parasitic Diseases Diagnoses with MCC
868	Other Infectious and Parasitic Diseases Diagnoses with CC
869	Other Infectious and Parasitic Diseases Diagnoses without CC/MCC
870	Septicemia or Severe Sepsis with MV >96 Hours
871	Septicemia or Severe Sepsis without MV >96 Hours with MCC
872	Septicemia or Severe Sepsis without MV >96 Hours without MCC
974	HIV with Major Related Condition with MCC
975	HIV with Major Related Condition with CC
976	HIV with Major Related Condition without CC/MCC

Typical Clinical Scenarios

An adult presents to the emergency department with acute onset of fever, severe jaw pain, swelling of the mandibular region, and a draining sinus tract after recent dental extraction. Examination and imaging show a localized cervicofacial abscess with sulfur granules on culture consistent with Actinomyces species; the clinician assigns a diagnosis from this group for acute cervicofacial actinomycosis. Typical codes: A42.0
A middle-aged patient with a history of prior chest surgery develops persistent cough, weight loss, and a chronic pulmonary consolidation on chest CT; bronchoscopy yields filamentous gram-positive bacteria consistent with actinomycosis causing thoracic involvement. Because the infection involves lung tissue with chronic symptoms and radiographic mass-like lesions, a thoracic actinomycosis code from this group is assigned. Typical codes: A42.1
A patient with poorly controlled diabetes presents for follow-up after recent abdominal surgery and now has a non-healing postoperative abdominal wall sinus and intra-abdominal abscess; cultures identify Actinomyces species contributing to an intra-abdominal/pelvic infection as a complication of the operative course. The diagnosis from this group is used to capture intra-abdominal actinomycosis as a postoperative complication/comorbidity affecting recovery. Typical codes: A42.2, A42.7

Related Codes

A30-LEPROSY-HANSEN-S-DISEASE

ICD-10-CM Code For Leprosy Hansen's Disease: Group Overview

A31-INFECTION-DUE-TO-OTHER-MYCOBACTERIA

ICD-10-CM Code For Infection Due To Other Mycobacteria: Group Overview

A32-LISTERIOSIS

ICD-10-CM Code For Listeriosis: Group Overview

A33-TETANUS-NEONATORUM

ICD-10-CM Code For Tetanus Neonatorum: Group Overview

A34-OBSTETRICAL-TETANUS

ICD-10-CM Code For Obstetrical Tetanus: Group Overview

A35-OTHER-TETANUS

ICD-10-CM Code For Other Tetanus: Group Overview

A36-DIPHTHERIA

ICD-10-CM Code For Diphtheria: Group Overview

A37-WHOOPING-COUGH

ICD-10-CM Code For Whooping Cough: Group Overview

A38-SCARLET-FEVER

ICD-10-CM Code For Scarlet Fever: Group Overview

A39-MENINGOCOCCAL-INFECTION

ICD-10-CM Code For Meningococcal Infection: Group Overview

Showing 1–10 of 16

Frequently Asked Questions

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

ICD-10-CM Code For Actinomycosis: Group Overview

Sign up for ICD-10-CM Code For Actinomycosis: Group Overview policy alerts

ICD-10-CM A42: Actinomycosis Overview

ICD-10-CM Code For Actinomycosis: Group Overview

Sign up for ICD-10-CM Code For Actinomycosis: Group Overview policy alerts

ICD-10-CM A42: Actinomycosis Overview

When to Use

ICD-10-CM Codes

DRG Codes

Typical Clinical Scenarios

Related Codes

Which diagnoses are included in the ICD-10-CM A42 group?

What clinical features of actinomycosis does the A42 group capture?

How does accurate coding in the A42 group affect reimbursement and claims?

Which DRGs are commonly related to actinomycosis coding in A42?

Which code should be used when the site of actinomycosis is not specified?

References

When to Use

ICD-10-CM Codes

DRG Codes

Typical Clinical Scenarios

Related Codes

Which diagnoses are included in the ICD-10-CM A42 group?

What clinical features of actinomycosis does the A42 group capture?

How does accurate coding in the A42 group affect reimbursement and claims?

Which DRGs are commonly related to actinomycosis coding in A42?

Which code should be used when the site of actinomycosis is not specified?

References