M05.19

Rheumatoid lung disease occurring concurrently with seropositive rheumatoid arthritis affecting multiple joint sites simultaneously, captured under a single billable code when bilateral or polyarticular involvement is present alongside pulmonary manifestation.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 5
Region: Multi-region

Drawn from CDCICD10DataCMSAAPCRhinomds

Documentation tips

What should appear in the chart to support M05.19.

Source · Editorial brief grounded in 5 cited references ↓

Document positive rheumatoid factor or anti-CCP antibody status explicitly — seropositive status is required for the entire M05.x category.
Name each affected joint site in the assessment/plan; 'multiple joints' without specifics still supports M05.19 but listing sites strengthens audit defense.
Record the pulmonary manifestation type (e.g., interstitial lung disease, rheumatoid nodules, pleuritis, pleural effusion) — 'rheumatoid lung disease' must be clinically supported, not just assumed.
Note any pulmonary function test results, high-resolution CT findings, or pulmonologist co-management that corroborate the lung involvement.
If the patient is on DMARDs or biologics, document that the pulmonary findings are attributable to RA rather than drug-induced, since drug-induced lung toxicity maps to a different code block.

Related CPT procedures

Procedure codes commonly billed with M05.19. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

27447 $1,159.35

Knee replacement surgery addressing both the medial and lateral tibiofemoral compartments, with or without resurfacing of the patella.

27130 $1,162.02

Primary total hip arthroplasty replacing both the acetabular socket and proximal femoral components with prosthetic implants, with or without bone graft.

94618 View procedure details

94621 View procedure details

71250 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M05.19 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Using M05.19 for seronegative RA with lung disease — seropositivity is required for all M05.x codes; seronegative cases belong in M06.x.
Defaulting to M05.19 when only one joint site is documented — single-site involvement requires a laterality-specific code (e.g., M05.161 for right knee).
Omitting a secondary code for the specific pulmonary condition when the payer or clinical context requires it — J99 (respiratory disorders in diseases classified elsewhere) may be needed as an additional code.
Conflating M05.19 with M05.9 (seropositive RA, unspecified) — M05.9 carries no lung disease component and will not support medical necessity for pulmonary procedures.
Failing to distinguish RA-associated lung disease from drug-induced pulmonary toxicity in patients on methotrexate or leflunomide, which requires a separate adverse effect code.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M05.19 is the correct code when a patient with seropositive rheumatoid arthritis has documented pulmonary involvement — such as interstitial lung disease, rheumatoid nodules in the lung, or pleuritis — and the joint disease affects multiple sites (e.g., both knees, wrists and shoulders, or other polyarticular patterns). The 'multiple sites' designation replaces separate site-specific codes from the M05.11–M05.17x range when documentation clearly identifies more than one distinct joint region as affected.

This code sits under parent M05.1 (Rheumatoid lung disease with rheumatoid arthritis) and requires seropositive RA — meaning positive rheumatoid factor or anti-CCP antibodies must be documented or implied. If seropositivity is not established, consider M06.09 (other seronegative RA, multiple sites) or the appropriate M06.x code. Do not use M05.19 for seronegative RA with lung disease.

CMS recognizes M05.19 as a supporting diagnosis for pulmonary procedures including pulmonary stress testing (CMS Article A56784), so accurate capture of this code directly affects medical necessity for respiratory workups ordered in the RA patient population. If only a single joint site is affected, drop to the site-specific M05.1x1/M05.1x2 code instead of defaulting to the multi-site code.

Sibling codes

Other billable codes under M05.1 (laterality / anatomic variants).

M05.10

Rheumatoid lung disease w rheumatoid arthritis of unsp site

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01Can M05.19 be used when RA affects only two joints on the same side?

Yes, if two distinct joint regions are involved (e.g., right knee and right shoulder) that does constitute multiple sites. However, document both sites explicitly so the 'multiple sites' designation is audit-defensible rather than inferred.

02Do I need to code the lung condition separately in addition to M05.19?

It depends on payer and clinical context. M05.19 captures the combined diagnosis, but some payers or clinical scenarios require an additional code for the specific pulmonary manifestation (e.g., J99 for respiratory disorders in diseases classified elsewhere). Check the applicable LCD or payer policy.

03What if the rheumatoid factor is negative but the provider documents RA with lung disease?

M05.x codes require seropositive RA. Seronegative RA with extra-articular manifestations maps to M06.09 (other seronegative RA, multiple sites) or another M06.x code depending on joint distribution. Verify serologic documentation before assigning any M05 code.

04Is M05.19 valid for pulmonary stress testing medical necessity under Medicare?

Yes. CMS Billing and Coding Article A56784 explicitly lists M05.19 as a supporting ICD-10-CM code for pulmonary stress testing, alongside other M05.1x site-specific codes.

05How does M05.19 differ from M05.10?

M05.10 is used when the joint site affected by RA is unspecified. M05.19 is used when multiple joint sites are documented. If the provider names more than one joint region, M05.19 is the more specific — and more defensible — choice.

06What is the effective date of M05.19 for FY2026?

M05.19 became effective October 1, 2025 under the FY2026 ICD-10-CM code set. The code itself has been valid since 2016 with no descriptor change for FY2026.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures joint-site distribution (bilateral, polyarticular, or named sites), serologic status (RF/anti-CCP positivity), and the specific pulmonary finding documented by the treating provider or consulting pulmonologist. This prevents downcoding to unspecified M05.9 and ensures the lung disease component is coded — a prerequisite for medical necessity on any associated respiratory diagnostic workup.

See how Mira captures M05.19 documentation