Skip to main content

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

Compare with another codeCheck this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
6 inclusion terms · 2 Excludes1
Risk adjustment
CMS-HCC V22 category 40 · RxHCC V08 category 84

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Excludes1Never report with this code
  • reactive perforating collagenosis (L87.1)
  • autoimmune disease, single organ or single cell-type -code to relevant condition category
IncludesWhat this code covers
  • autoimmune disease NOS
  • collagen (vascular) disease NOS
  • systemic autoimmune disease
  • systemic collagen (vascular) disease

+2 more in Instructions

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 545 — CONNECTIVE TISSUE DISORDERS WITH MCC (MDC 08)
  • MS-DRG 546 — CONNECTIVE TISSUE DISORDERS WITH CC (MDC 08)
  • MS-DRG 547 — CONNECTIVE TISSUE DISORDERS WITHOUT CC/MCC (MDC 08)

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.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for M35.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on M35.9 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

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

Source: inherited from M30-M36

Inclusion Terms

Alternative terms the tabular list files under this code.

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

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

  • reactive perforating collagenosis (L87.1) inherited from M35Compare M35.9 vs L87.1 →
  • autoimmune disease, single organ or single cell-type -code to relevant condition category inherited from M30-M36

Coder workflow for M35.9

MedCoder structured workflow — derived from this code’s own official record

Before you code M35.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, M35.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewM35.0, M35.1, M35.2, M35.3, M35.4, M35.5, M35.6, M35.7

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with M35.9. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — M35.9 is appropriate when the documentation goes no further.

    ReviewM35.0, M35.1, M35.2, M35.3, M35.4, M35.5, M35.6, M35.7

  2. Does the documentation support a condition named in M35.9’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewL87.1

Consider M35.9. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting M35.9(2 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with M35.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareL87.1

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewM35.0, M35.1, M35.2, M35.3, M35.4, M35.5, M35.6, M35.7

Documentation: Both the condition M35.9 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewL87.1

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse M35.9 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of M35.9 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • L87.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of reactive perforating collagenosis moves the case to L87.1; the two are not reported together unless documented as unrelated.

    Full comparison: M35.9 vs L87.1 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Systemic involvement of connective tissue, unspecified is a billable ICD-10-CM diagnosis code (M35.9).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name M35.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 9 Excludes1 notes across 2 chapters: D80 — Immunodeficiency with predominantly antibody defects, D80-D89 — Certain disorders involving the immune mechanism (D80-D89), D81 — Combined immunodeficiencies, D82 — Immunodeficiency associated with other major defects, D83 — Common variable immunodeficiency, D84 — Other immunodeficiencies, D86 — Sarcoidosis, D89 — Other disorders involving the immune mechanism, not elsewhere classified, L94 — Other localized connective tissue disorders (via M35.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 2 Excludes2 notes across 2 chapters: I77 — Other disorders of arteries and arterioles (via M35.-), J82 — Pulmonary eosinophilia, not elsewhere classified (via M35.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 2 Code First instructions across 2 chapters: G32.81 — Cerebellar ataxia in diseases classified elsewhere, J84.170 — Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere (via M35.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 3 MS-DRGs: DRG 545 (MDC 08), DRG 546 (MDC 08), DRG 547 (MDC 08).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MUS024 — Systemic lupus erythematosus and connective tissue disorders (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Systemic lupus erythematosus and connective tissue disorders).

M35.05 — Sjögren syndrome with inflammatory arthritis, M35.06 — Sjögren syndrome with peripheral nervous system involvement, M35.07 — Sjögren syndrome with central nervous system involvement, M35.08 — Sjögren syndrome with gastrointestinal involvement, M35.09 — Sjögren syndrome with other organ involvement, M35.0A — Sjögren syndrome with glomerular disease, M35.0B — Sjögren syndrome with vasculitis, M35.0C — Sjögren syndrome with dental involvement, M35.1 — Other overlap syndromes, M35.2 — Behçet's disease, M35.3 — Polymyalgia rheumatica, M35.4 — Diffuse (eosinophilic) fasciitis, M35.5 — Multifocal fibrosclerosis, M35.6 — Relapsing panniculitis [Weber-Christian], M35.7 — Hypermobility syndrome, M35.8 — Other specified systemic involvement of connective tissue, M35.81 — Multisystem inflammatory syndrome, M35.89 — Other specified systemic involvement of connective tissue, M36.0 — Dermato(poly)myositis in neoplastic disease, M36.8 — Systemic disorders of connective tissue in other diseases classified elsewhere, +72 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Polyneuropathy”, “Skin”, “Ataxia, ataxy, ataxic”, …; these codes share that main term but sit in a different category of the Tabular List.

G65.1 — Sequelae of other inflammatory polyneuropathy (inflammatory, sequelae), G65.2 — Sequelae of toxic polyneuropathy (lead, sequelae), I42.89 — Other cardiomyopathies not elsewhere classified (cardiovascular), I69.093 — Ataxia following nontraumatic subarachnoid hemorrhage (following, cerebrovascular disease, subarachnoid hemorrhage), I69.193 — Ataxia following nontraumatic intracerebral hemorrhage (following, cerebrovascular disease, intracerebral hemorrhage), I69.293 — Ataxia following other nontraumatic intracranial hemorrhage (following, cerebrovascular disease, nontraumatic intracranial hemorrhage NEC), I69.393 — Ataxia following cerebral infarction (following, cerebrovascular disease, cerebral infarction), I69.893 — Ataxia following other cerebrovascular disease (following, cerebrovascular disease, specified disease NEC), I69.993 — Ataxia following unspecified cerebrovascular disease (following, cerebrovascular disease), K90.0 — Celiac disease (gluten, with celiac disease), L85.3 — Xerosis cutis (dry), L87.1 — Reactive perforating collagenosis (reactive perforating), M30.0 — Polyarteritis nodosa (in, polyarteritis nodosa), M31.7 — Microscopic polyangiitis (in, microscopic polyangiitis), M32.19 — Other organ or system involvement in systemic lupus erythematosus (in, systemic, lupus erythematosus), N18.9 — Chronic kidney disease, unspecified (in, uremia), R23.1 — Pallor (clammy), R26.0 — Ataxic gait (gait), R27.0 — Ataxia, unspecified, R27.8 — Other lack of coordination (acute), +60 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Thyroid Stimulating Hormone (TSH)

Contextual Map

Every relationship of M35.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run M35.9 with these 12 related codes in Claim Check

Hierarchy

Index manifestation

Referenced by Excludes1 notes (9)

Referenced by Excludes2 notes

Referenced by Code First instructions

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 08 — Diseases and Disorders of the Musculoskeletal System and Connective Tissue[MDC crossing]: “Diseases and Disorders of the Musculoskeletal System and Connective Tissue — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 18,439 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (12)

  • Ataxia, ataxy, ataxic, gluten[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Autoimmune, disease (systemic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Collagenosis, collagen disease (nonvascular) (vascular)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, autoimmune NOS (systemic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, collagen NOS (nonvascular) (vascular)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, connective tissue, systemic (diffuse)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Disease, diseased, mesenchymal[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Dyscollagenosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • and 4 more

Nearest codes (25)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Indexed Clinical Terms (12)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 20, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "M35.9 — Systemic involvement of connective tissue, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/m35.9-systemic-involvement-of-connective-tissue-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Systemic involvement of connective tissue, unspecified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to M35.9 in its code family, with their registry titles.

View all codes in the M35 family