2026 ICD-10-CM Diagnosis Code R91Abnormal findings on diagnostic imaging of lung

ICD-10-CM Codes›R00–R99›R90-R94›R91

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

R91 is a non-billable ICD-10-CM category code for abnormal findings on diagnostic imaging of lung, so it cannot be submitted on claims. Use a more specific code from this category instead, such as R91.1 and R91.8. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established.

Code Identity

ICD-10-CM Code
R91
Billable Status
No — Non-Billable Category
Code Describes
Abnormal findings on diagnostic imaging of lung
Short Description
Abnormal findings on diagnostic imaging of lung
Same as the full description in the CMS dataset.
Chapter
R90-R94
Abnormal findings on diagnostic imaging and in function studies, without diagnosis

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 CodeR91Abnormal findings on diagnostic imaging of lung

Specific Coding for Abnormal findings on diagnostic imaging of lungOverview

Non-specific codes like R91 require more characters. Use one of these billable codes instead:

  • Use R91.1 for Solitary pulmonary nodule

  • Use R91.8 for Other nonspecific abnormal finding of lung field

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 R91Overview

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

No. This is a category header that groups the codes for abnormal findings on diagnostic imaging of lung, and headers cannot be submitted on claims. Claims for abnormal findings on diagnostic imaging of lung need a more specific code from this category, such as R91.1 and R91.8.

Can R91 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the abnormal findings on diagnostic imaging of lung is established, that condition takes the principal position instead.