2026 ICD-10-CM Diagnosis Code M35.89Other specified systemic involvement of connective tissue

ICD-10-CM Codes›M00–M99›M30-M36›M35

ICD-10-CM M35.89
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M35.89 is a billable ICD-10-CM diagnosis code for other specified systemic involvement of connective tissue. 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 2 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders.

M35.89 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 40 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 40, ESRD (V21) category 40, ESRD (V24) category 40, and RxHCC Part D (V08) category 84 for payment year 2026.

Code Identity

ICD-10-CM Code
M35.89
Billable Status
Yes — Valid for Submission
Code Describes
Other specified systemic involvement of connective tissue
Short Description
Other specified systemic involvement of connective tissue
Same as the full description in the CMS dataset.
Parent Code
M35.8
Other specified 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 CodeM35.89Other specified systemic involvement of connective tissue

Medicare Risk Adjustment (HCC)Billing

M35.89 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 40
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 40 · ESRD (V21): HCC 40 · ESRD (V24): HCC 40
ESRD V21 weights: 0.072 dialysis, 0.274–0.398 functioning graft · ESRD V24 weights: 0.058 dialysis, 0.284–0.414 functioning graft
Part D (RxHCC)
RxHCC 84 — Systemic Lupus Erythematosus and Other Systemic Connective Tissue Disorders
also risk-adjusts in the Part D prescription drug model (V08)

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Antisynthetase syndrome
  • Anti-synthetase syndrome due to dermatomyositis
  • Antisynthetase syndrome due to polymyositis
  • Collagen deficiency syndrome
  • Cranial cerebrospinal fluid leak
  • EMILIN-1-related connective tissue disease
  • Eosinophilia myalgia syndrome
  • Eosinophilia-myalgia syndrome from tryptophan
  • Leak of cranial cerebrospinal fluid due to collagen deficiency syndrome
  • Marden Walker syndrome
  • Muscle eosinophilia
  • Polyneuropathy in collagen malignant disease
  • Satoyoshi syndrome

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

  • Autoimmune Hypophysitis|Lymphocytic Hypophysitis

    an autoimmune condition affecting the pituitary gland, characterized by lymphocytic infiltration, commonly presenting with pituitary hormone deficiencies.

  • Grade 1 Hypophysitis, CTCAE|Grade 1 Hypophysitis

    asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated

  • Grade 2 Hypophysitis, CTCAE|Grade 2 Hypophysitis

    moderate; minimal, local or noninvasive intervention indicated; limiting age-appropriate instrumental adl

  • Grade 3 Hypophysitis, CTCAE|Grade 3 Hypophysitis

    severe or medically significant but not immediately life-threatening; hospitalization or prolongation of existing hospitalization indicated; limiting self care adl

  • Grade 4 Hypophysitis, CTCAE|Grade 4 Hypophysitis

    life-threatening consequences; urgent intervention indicated

  • Grade 5 Hypophysitis, CTCAE|Grade 5 Hypophysitis

    death

  • Hypophysitis

    an inflammatory process in the pituitary gland.

  • Hypophysitis, CTCAE|Hypophysitis

    a disorder characterized by inflammation and cellular infiltration of the pituitary gland.

  • Lymphocytic Neurohypophysitis

    an autoimmune condition affecting the posterior pituitary gland, which is characterized by lymphocytic infiltration, and which often presents as diabetes insipidus.

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.

Code History & ChangesHistory

Replacement M35.89 replaces the following previously assigned code(s):

  • M35.8 - Other specified systemic involvement of connective tissue
FY 2022AddedAdded to the ICD-10-CM code setEffective October 1, 2021.
FY 2023–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M35.89Overview

What is the ICD-10 code for other specified systemic involvement of connective tissue?

The ICD-10-CM code for other specified systemic involvement of connective tissue is M35.89 (sometimes written as M3589). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is M35.89 (Other specified systemic involvement of connective tissue) a billable code?

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

What MS-DRG does M35.89 group to?

When other specified systemic involvement of connective tissue 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.

Is M35.89 a CC or MCC?

CMS lists M35.89 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 2 closely related codes in its exclusion list.

Does M35.89 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. M35.89 mapped to HCC 40 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease), ESRD (V21) category 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease), ESRD (V24) category 40 (Rheumatoid Arthritis and Inflammatory Connective Tissue Disease), and RxHCC Part D (V08) category 84 (Systemic Lupus Erythematosus and Other Systemic Connective Tissue Disorders).