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R91.8

R91.8Other nonspecific abnormal finding of lung field

Billable / specific codeICD-10-CM

R91.8 is a billable, specific ICD-10-CM code for other nonspecific abnormal finding of lung field. It is valid for submission on a claim.

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

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

Risk adjustment

R91.8 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Medicare coverage

R91.8 is named in 11 Medicare coverage policies 11 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A56580Billing and Coding: Computerized Axial Tomography (CT), Thorax
  • A56612Billing and Coding: CT of the Head
  • A56717Billing and Coding: Respiratory Therapy (Respiratory Care)
  • A56929Billing and Coding: BDX-XL2

How R91.8 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to R91.8.

  • Shadow, lung
  • Infiltrate, infiltrationlung
  • Infiltrate, infiltrationon chest x-ray
  • Infiltrate, infiltrationpulmonary
  • Masslung
  • Abnormal, abnormality, abnormalitiesdiagnostic imaginglung(field)
  • Nodule, nodularlung, solitarymultiple
  • Nodule, nodularsolitary, lungmultiple

Related codes at this level

Codes that share R91. If R91.8 is not quite right, the correct code is usually one of these.

Questions about R91.8

Is R91.8 a billable ICD-10-CM code?
Yes. R91.8 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does R91.8 sit in the tabular list?
Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99), in the block Abnormal findings on diagnostic imaging and in function studies, without diagnosis (R90-R94).
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.