Is ICD-10-CM code M35 billable?

No, M35 (Other systemic involvement of connective tissue) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code M35 belong to?

M35 belongs to Chapter 13 of the ICD-10-CM tabular list: M00–M99 (Diseases of the Musculoskeletal System and Connective Tissue).

M35Not billable, use a more specific code below

Other systemic involvement of connective tissue

In Systemic connective tissue disorders (M30-M36), chapter 13: Diseases of the Musculoskeletal System and Connective Tissue

23 billable codes under M35: 7 are a CC; 3 map to HCC 2 (Septicemia, Sepsis, Systemic Inflammatory Response Syndrome/Shock), HCC 94 (Systemic Lupus Erythematosus and Other Specified Systemic Connective Tissue Disorders), HCC 280 (Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders).A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment. An HCC counts toward a Medicare Advantage patient's risk score.

Instructional notes

Excludes1: not coded here, use a different code

reactive perforating collagenosis (L87.1)

Also applies, from Systemic connective tissue disorders (M30-M36)

These notes sit on M30-M36 and apply to every code under it, including M35.

Includes: conditions that are coded here

autoimmune disease NOS
collagen (vascular) disease NOS
systemic autoimmune disease
systemic collagen (vascular) disease

Excludes1: not coded here, use a different code

autoimmune disease, single organ or single cell-type -code to relevant condition category

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers site and laterality, acute injury versus chronic musculoskeletal conditions, 7th characters for pathologic fractures, osteoporosis with or without current fracture, and multisystem inflammatory syndrome.

Site and laterality (page 60)
Acute traumatic versus chronic or recurrent musculoskeletal conditions (page 61)
Coding of Pathologic Fractures (page 61)
Osteoporosis (page 61)
Multisystem Inflammatory Syndrome (page 62)

Read Section I.C.13 (page 60)

All codes under M35

M35 can't be used on a claim. Pick a billable code below; grey headings group them.

M35 MS-DRGs

As the principal diagnosis, the billable codes under M35 group to these 7 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

DRG 545 Connective Tissue Disorders with MCC (20 of 23 codes)
DRG 546 Connective Tissue Disorders with CC (20 of 23 codes)
DRG 547 Connective Tissue Disorders without CC/MCC (20 of 23 codes)
DRG 557 Tendonitis, Myositis and Bursitis with MCC (2 of 23 codes)
DRG 558 Tendonitis, Myositis and Bursitis without MCC (2 of 23 codes)
DRG 606 Minor Skin Disorders with MCC (1 of 23 codes)
DRG 607 Minor Skin Disorders without MCC (1 of 23 codes)

Other codes that refer to M35

Notes on these codes point to M35.

Q87.A Excludes1: other systemic involvement of connective tissue (M35)

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Connective Tissue Disorders

Your connective tissue supports many different parts of your body, such as your skin, eyes, and heart. It is like a "cellular glue" that gives your body parts their shape and helps keep them strong. It also helps some of your tissues do their work. It is made of many kinds of proteins. Cartilage and fat are types of connective tissue.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.