2026 ICD-10-CM Diagnosis Code M35.9Systemic involvement of connective tissue, unspecified

ICD-10-CM Codes›M00–M99›M30-M36›M35

ICD-10-CM M35.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M35.9 is a billable ICD-10-CM diagnosis code for systemic involvement of connective tissue, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 545 through 547. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders.

Code Identity

ICD-10-CM Code
M35.9
Billable Status
Yes — Valid for Submission
Code Describes
Systemic involvement of connective tissue, unspecified
Short Description
Systemic involvement of connective tissue, unspecified
Same as the full description in the CMS dataset.
Parent Code
M35
Other systemic involvement of connective tissue

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM30-M36Systemic connective tissue disorders
CategoryM35Other systemic involvement of connective tissue
This CodeM35.9Systemic involvement of connective tissue, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired poikiloderma
  • Acquired sensorineural hearing loss
  • Associated pulmonary arterial hypertension
  • Autoimmune connective tissue disorder
  • Autoimmune disease
  • Autoimmune disorder of autonomic nerve
  • Autoimmune disorder of autonomic nervous system
  • Autoimmune esophagitis
  • Autoimmune ganglionopathy
  • Autoimmune inflammation of skeletal muscle
  • Autoimmune leukopenia
  • Autoimmune necrotizing myopathy
  • Autoimmune opsoclonus myoclonus
  • Autoimmune optic neuropathy
  • Autoimmune pancytopenia
  • Autoimmune sensorineural hearing loss
  • Autoimmune skin disease
  • Cardiomyopathy due to connective tissue disease
  • Chronic tubulo-interstitial nephritis due to connective tissue disorder
  • Collagen and elastic tissue disorders affecting skin
  • Collagen disease
  • Congenital connective tissue disorder
  • Conjunctivitis associated with autoimmune skin disorder
  • Connective tissue disease overlap syndrome
  • Connective tissue hereditary disorder
  • Dilated cardiomyopathy with connective tissue disorder
  • Disorder of connective tissue co-occurrent and due to systemic disease
  • Disseminated eosinophilic collagen disease
  • Fetal disorder due to maternal autoimmune disease
  • Idiopathic inflammatory myopathy
  • Immune neutropenia
  • Interstitial lung disease due to collagen vascular disease
  • Interstitial lung disease due to connective tissue disease
  • Lung disease due to connective tissue disorder
  • Lung disorder due to autoimmune disorder
  • Metabolic disease of collagen
  • Mixed collagen vascular disease
  • Myocarditis due to autoimmune disease
  • Necrotizing vasculitis secondary to connective tissue disease
  • Neutropenia associated with autoimmune disease
  • Noninfectious enteritis due to autoimmune disease
  • Non-infectious ulceration of small intestine due to autoimmune disease
  • Non-infective ulceration of small intestine
  • Opsoclonus-myoclonus syndrome
  • Overlap syndrome
  • Pediatric autoimmune neuropsychiatric disorder associated with streptococcal infection
  • Pericarditis secondary to collagen vascular disease
  • Photodermatitis co-occurrent and due to autoimmune disease
  • Poikiloderma due to connective tissue disease
  • Polymyositis
  • Polymyositis associated with autoimmune disease
  • Polyneuropathy co-occurrent and due to systemic connective tissue disorder
  • Polyneuropathy in collagen vascular disease
  • Pulmonary arterial hypertension associated with connective tissue disease
  • Raynaud phenomenon due to autoimmune disease
  • Raynaud's phenomenon
  • Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations
  • Secondary Raynaud's phenomenon
  • Small vessel cerebrovascular disease
  • Xerostomia
  • Xerostomia due to autoimmune disease

Tabular List NotesGuidance

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

Inclusion Terms

  • Autoimmune disease (systemic) NOS
  • Collagen (vascular) disease NOS

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.

    • Ataxia, ataxy, ataxic
      • gluten
    • Autoimmune
      • disease (systemic)
    • Collagenosis, collagen disease(nonvascular) (vascular)
    • Disease, diseased
      • autoimmune (systemic) NOS
    • Disease, diseased
      • collagen NOS (nonvascular) (vascular)
    • Disease, diseased
      • connective tissue, systemic (diffuse)
    • Disease, diseased
      • mesenchymal
    • Dyscollagenosis
    • Polyneuropathy(peripheral)
      • in (due to)
        • collagen vascular disease NEC
    • Polyneuropathy(peripheral)
      • in (due to)
        • systemic
          • connective tissue disorder
    • Skin
      • hidebound
    • Syndrome
      • connective tissue

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS024
Systemic lupus erythematosus and connective tissue disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Dermatomyositis

    a subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. the illness occurs with approximately equal frequency in children and adults. the skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. the disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. the childhood form of this disease tends to evolve into a systemic vasculitis. dermatomyositis may occur in association with malignant neoplasms. (from adams et al., principles of neurology, 6th ed, pp1405-6)

  • Polymyositis

    diseases characterized by inflammation involving multiple muscles. this may occur as an acute or chronic condition associated with medication toxicity (drug toxicity); connective tissue diseases; infections; malignant neoplasms; and other disorders. the term polymyositis is frequently used to refer to a specific clinical entity characterized by subacute or slowly progressing symmetrical weakness primarily affecting the proximal limb and trunk muscles. the illness may occur at any age, but is most frequent in the fourth to sixth decade of life. weakness of pharyngeal and laryngeal muscles, interstitial lung disease, and inflammation of the myocardium may also occur. muscle biopsy reveals widespread destruction of segments of muscle fibers and an inflammatory cellular response. (adams et al., principles of neurology, 6th ed, pp1404-9)

  • Xerostomia

    decreased salivary flow.

  • Exosome Component 10|Autoantigen PM-SCL|Autoantigen PM/Scl|EC 3.1.13.-|EXOSC10|P100 Polymyositis-Scleroderma Overlap Syndrome-Associated Autoantigen|PM/Scl-100|Polymyositis/Scleroderma Autoantigen 100 kDa|Polymyositis/Scleroderma Autoantigen 2

    exosome component 10 (885 aa, ~101 kda) is encoded by the human exosc10 gene. this protein plays a role in the maturation and degradation of rna.

  • Other Overlap Syndromes|Other overlap syndromes

    evidence of other overlap syndromes not specified elsewhere.

  • Overlap Syndrome

    an autoimmune, connective tissue disorder in which the patient exhibits features from two or more diseases. these typically include systemic sclerosis, dermatomyositis, polymyositis, rheumatoid arthritis, systemic lupus erythematosus, and sjogren syndrome; in pediatrics the respective pediatric entities are encountered.

  • Scleroderma Polymyositis Overlap Syndrome|Scleroderma Polymyositis

    a rare autoimmune disorder in which patients present with overlapping symptoms of systemic scleroderma and polymyositis or dermatomyositis.

  • Exosome Complex Component RRP45|AMPA RECEPTORS|Autoantigen PM/Scl 1|EXOSC9|Exosome Component 9|GLuRs|P75 Polymyositis-Scleroderma Autoantigen|P75 Polymyositis-Scleroderma Overlap Syndrome Associated Autoantigen|P75 Polymyositis-Scleroderma Overlap Syndrome-Associated Autoantigen|PM/Scl-75|Polymyositis/Scleroderma Autoantigen 1|Polymyositis/Scleroderma Autoantigen 75 kDa

    exosome complex component rrp45 (439 aa, ~49 kda) is encoded by the human exosc9 gene. this protein is involved in the regulation of the exoribonuclease activity of the exosome.

  • Exosome Component 10|Autoantigen PM-SCL|Autoantigen PM/Scl|EC 3.1.13.-|EXOSC10|EXOSC10|P100 POLYMYOSITIS-SCLERODERMA AUTOANTIGEN|P100 Polymyositis-Scleroderma Overlap Syndrome-Associated Autoantigen|PM/Scl 2|PM/Scl-100|PM/Scl-100|Polymyositis/Scleroderma Autoantigen 100 kDa|Polymyositis/Scleroderma Autoantigen 2|Polymyositis/Scleroderma Autoantigen 2

    exosome component 10 (885 aa, ~101 kda) is encoded by the human exosc10 gene. this protein plays a role in the maturation and degradation of rna.

  • Autoimmune Neutropenia|AIN|AIN

    a condition characterized by the autoantibody-induced destruction of neutrophils.

  • Immune Neutropenia

    neutropenia caused by immune destruction of mature neutrophils. it may be further categorized as autoimmune, alloimmune, drug-induced, or idiopathic immune neutropenia.

Patient EducationClinical

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.

Read the full article at MedlinePlus

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

Convert M35.9 to ICD-9-CMHistory

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

ICD-9-CM
710.9 Diff connect tis dis NOS
Approximate The match is approximate rather than exact.

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 M35.9Overview

Is M35.9 (Other systemic involvement of connective tissue) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report systemic involvement of connective tissue, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M35.9 group to?

When systemic involvement of connective tissue, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M35.9?

Under the General Equivalence Mappings, systemic involvement of connective tissue, unspecified converts to ICD-9-CM 710.9 (diff connect tis dis NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.