2026 ICD-10-CM Diagnosis Code R91.8Other nonspecific abnormal finding of lung field

ICD-10-CM Codes›R00–R99›R90-R94›R91

ICD-10-CM R91.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R91.8 is a billable ICD-10-CM diagnosis code for other nonspecific abnormal finding of lung field. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Abnormal findings without diagnosis.

Code Identity

ICD-10-CM Code
R91.8
Billable Status
Yes — Valid for Submission
Code Describes
Other nonspecific abnormal finding of lung field
Short Description
Other nonspecific abnormal finding of lung field
Same as the full description in the CMS dataset.
Parent Code
R91
Abnormal findings on diagnostic imaging of lung

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR90-R94Abnormal findings on diagnostic imaging and in function studies, without diagnosis
CategoryR91Abnormal findings on diagnostic imaging of lung
This CodeR91.8Other nonspecific abnormal finding of lung field

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abnormal findings on diagnostic imaging of lung
  • Air bronchogram
  • Air crescent sign
  • Bilateral lung opacities on plain chest X-ray
  • Bronchography abnormal
  • Bronchoscopy abnormal
  • Endoscopy abnormal
  • Finding of lung field
  • Ground glass opacity
  • Hilar mass
  • Imaging of lung abnormal
  • Imaging of lung consistent with tuberculosis
  • Increased lung tracer uptake
  • Increased markings
  • Increased vascular markings of lung
  • Lesion of lung
  • Lung field abnormal
  • Lung mass
  • Mass of right lower lobe of lung
  • Mottling
  • Mottling of lung
  • Multilobar lung infiltrate
  • Opacity on plain X-ray
  • Plain X-ray of chest abnormal
  • Radiologic increased density of lung
  • Radiologic infiltrate
  • Radiologic infiltrate of lung
  • Shadow
  • Shadow of lung
  • Single lobe lung infiltrate
  • Ultrasonography of lung abnormal

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Lung mass NOS found on diagnostic imaging of lung
  • Pulmonary infiltrate NOS
  • Shadow, lung

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Abnormal, abnormality, abnormalities
      • diagnostic imaging
        • lung (field)
    • Infiltrate, infiltration
      • lung
    • Infiltrate, infiltration
      • on chest x-ray
    • Infiltrate, infiltration
      • pulmonary
    • Mass
      • lung
    • Nodule(s), nodular
      • lung, solitary (subsegmental branch of the bronchial tree)
        • multiple
    • Nodule(s), nodular
      • solitary, lung (subsegmental branch of the bronchial tree)
        • multiple
    • Shadow, lung

Clinical ClassificationClinical

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

CCSR SYM017
Abnormal findings without diagnosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Convert R91.8 to ICD-9-CMHistory

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

ICD-9-CM
793.19 Ot nonsp ab fnd lung fld
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R91.8Overview

Is R91.8 (Abnormal findings on diagnostic imaging of lung) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other nonspecific abnormal finding of lung field on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can R91.8 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the other nonspecific abnormal finding of lung field is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R91.8?

Under the General Equivalence Mappings, other nonspecific abnormal finding of lung field converts to ICD-9-CM 793.19 (ot nonsp ab fnd lung fld). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.