2026 ICD-10-CM Diagnosis Code R91.1Solitary pulmonary nodule

ICD-10-CM Codes›R00–R99›R90-R94›R91

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

R91.1 is a billable ICD-10-CM diagnosis code for solitary pulmonary nodule. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 205 through 206. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. Coders also document this condition as coin lesion of lung. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Abnormal findings without diagnosis.

Code Identity

ICD-10-CM Code
R91.1
Billable Status
Yes — Valid for Submission
Code Describes
Solitary pulmonary nodule
Short Description
Solitary pulmonary nodule
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 CodeR91.1Solitary pulmonary nodule

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Coin lesion of lung
  • Infection of lung caused by Pneumocystis
  • Nodule of lung
  • Pneumocystosis
  • Pulmonary nodule caused by Pneumocystis
  • Pulmonary nodule following infection by Coccidioides
  • Solitary nodule of lung

Tabular List NotesGuidance

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

Inclusion Terms

  • Coin lesion lung
  • Solitary pulmonary nodule, subsegmental branch of the bronchial tree

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.

    • Lesion(s) (nontraumatic)
      • coin, lung
    • Lesion(s) (nontraumatic)
      • lung (coin)
    • Nodule(s), nodular
      • lung, solitary (subsegmental branch of the bronchial tree)
    • Nodule(s), nodular
      • pulmonary, solitary (subsegmental branch of the bronchial tree)
    • Nodule(s), nodular
      • solitary, lung (subsegmental branch of the bronchial tree)

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

Clinical InformationClinical

  • Solitary Pulmonary Nodule

    a single lung lesion that is characterized by a small round mass of tissue, usually less than 1 cm in diameter, and can be detected by chest radiography. a solitary pulmonary nodule can be associated with neoplasm, tuberculosis, cyst, or other anomalies in the lung, the chest wall, or the pleura.

Patient EducationClinical

Lung Diseases

When you breathe, your lungs take in oxygen from the air and deliver it to the bloodstream. The cells in your body need oxygen to work and grow. During a normal day, you breathe nearly 25,000 times. People with lung disease have difficulty breathing. Millions of people in the U.S. have lung disease.

Read the full article at MedlinePlus

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

Convert R91.1 to ICD-9-CMHistory

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

ICD-9-CM
793.11 Solitary pulmonry nodule
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 R91.1Overview

Is R91.1 (Abnormal findings on diagnostic imaging of lung) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report solitary pulmonary nodule on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does R91.1 group to?

When solitary pulmonary nodule is the principal diagnosis on an inpatient stay, it groups to MS-DRG 205, 206, with relative weights from 0.9411 to 1.8310 depending on complications. Higher weights mean higher Medicare reimbursement.

Can R91.1 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the solitary pulmonary nodule is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R91.1?

Under the General Equivalence Mappings, solitary pulmonary nodule converts to ICD-9-CM 793.11 (solitary pulmonry nodule). 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.