M05.161 ICD-10-CM Code: Rheumatoid lung disease with rheumatoid arthritis of right knee
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Inpatient Payment Groups (MS-DRG)
MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.
- MS-DRG 196 — INTERSTITIAL LUNG DISEASE WITH MCC (MDC 04)
- MS-DRG 197 — INTERSTITIAL LUNG DISEASE WITH CC (MDC 04)
- MS-DRG 198 — INTERSTITIAL LUNG DISEASE WITHOUT CC/MCC (MDC 04)
A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.
Risk Adjustment (CMS-HCC)
Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.
- HCC 93 — Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders (supersedes HCC 94)
Other models: CMS-HCC V22 HCC 40 · RxHCC V08 HCC 83
Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.
Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.
Official Registry Overview & Definition
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for M05.161 in the official ICD-10-CM tabular list.
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- rheumatic fever (I00)
- juvenile rheumatoid arthritis (M08.-)
- rheumatoid arthritis of spine (M45.-)
Nearest Codes in This Family
Official ICD-10-CM classifications closest to M05.161 in its code family, with their registry titles.
- M05.15 — Rheumatoid lung disease with rheumatoid arthritis of hip
- M05.151 — Rheumatoid lung disease with rheumatoid arthritis of right hip
- M05.152 — Rheumatoid lung disease with rheumatoid arthritis of left hip
- M05.159 — Rheumatoid lung disease with rheumatoid arthritis of unspecified hip
- M05.16 — Rheumatoid lung disease with rheumatoid arthritis of knee
- M05.162 — Rheumatoid lung disease with rheumatoid arthritis of left knee
- M05.169 — Rheumatoid lung disease with rheumatoid arthritis of unspecified knee
- M05.17 — Rheumatoid lung disease with rheumatoid arthritis of ankle and foot
- M05.171 — Rheumatoid lung disease with rheumatoid arthritis of right ankle and foot
- M05.172 — Rheumatoid lung disease with rheumatoid arthritis of left ankle and foot