2027 ICD-10-CM Diagnosis Code A43.1Cutaneous nocardiosis

ICD-10-CM Codes›A00–B99›A30-A49›A43

ICD-10-CM A43.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

A43.1 is a billable ICD-10-CM diagnosis code for cutaneous nocardiosis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 606 through 607, 974 through 976. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 9 closely related codes. Coders also document this condition as actinomycetoma caused by Nocardia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Skin and subcutaneous tissue infections.

Code Identity

ICD-10-CM Code
A43.1
Billable Status
Yes — Valid for Submission
Code Describes
Cutaneous nocardiosis
Short Description
Cutaneous nocardiosis
Same as the full description in the CMS dataset.
Parent Code
A43
Nocardiosis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA43Nocardiosis
This CodeA43.1Cutaneous nocardiosis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Actinomycetoma caused by Nocardia
  • Actinomycetoma caused by Nocardia asteroides
  • Actinomycetoma caused by Nocardia brasiliensis
  • Actinomycetoma caused by Nocardia otitidis caviarum
  • Cutaneous nocardiosis
  • Disseminated nocardiosis
  • Disseminated nocardiosis infection affecting skin
  • Primary cutaneous nocardiosis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to A43.1: its own notes plus those printed at Chapter 1. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • diseases generally recognized as communicable or transmissible

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • carrier or suspected carrier of infectious disease (Z22.-)
  • certain localized infections - see body system-related chapters
  • infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
  • infectious and parasitic diseases specific to the perinatal period (P35-P39)
  • influenza and other acute respiratory infections (J00-J22)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Chapter 1 (A00-B99) Certain infectious and parasitic diseases applies to 1,068 codes
  • code to identify resistance to antimicrobial drugs (Z16.-)

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR SKN001
Skin and subcutaneous tissue infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Nocardia Infections

    infections with bacteria of the genus nocardia.

Patient EducationClinical

Bacterial Infections

Bacteria are tiny organisms (living things) that have only one cell. Under a microscope, they look like balls, rods, or spirals. They can be found almost everywhere on Earth. There are lots of bacteria in and on your body. In fact, your body has about 10 times more bacteria cells than human cells.

The full article covers:

  • What are bacteria?
  • How do bacterial infections spread?
  • What are the treatments for bacterial infections?
  • Can bacterial infections be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A43.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
039.0 Cutaneous actinomycosis
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About A43.1Overview

What is the ICD-10 code for cutaneous nocardiosis?

The ICD-10-CM code for cutaneous nocardiosis is A43.1 (sometimes written as A431). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is A43.1 (Nocardiosis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cutaneous nocardiosis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does A43.1 group to?

When cutaneous nocardiosis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 974, 976, 607, 975, 606, with relative weights from 0.7879 to 3.0488 depending on complications. Higher weights mean higher Medicare reimbursement.

Is A43.1 a CC or MCC?

CMS lists A43.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 9 closely related codes in its exclusion list.

What is the ICD-9 equivalent of A43.1?

Under the General Equivalence Mappings, cutaneous nocardiosis converts to ICD-9-CM 039.0 (cutaneous actinomycosis). The mapping is approximate, so confirm the match fits the documentation.