2026 ICD-10-CM Diagnosis Code M35.5Multifocal fibrosclerosis
ICD-10-CM Codes›M00–M99›M30-M36›M35
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Chronic Condition
M35.5 is a billable ICD-10-CM diagnosis code for multifocal fibrosclerosis. 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 6 closely related codes. Coders also document this condition as fibrosclerosis - systemic. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Systemic lupus erythematosus and connective tissue disorders.
M35.5 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
Code Classification
Medicare Risk Adjustment (HCC)Billing
M35.5 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.
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.
- Fibrosclerosis - systemic
- Multifocal fibrosclerosis
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
multifocal M35.5
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
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 M35.5 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M35.5Overview
What is the ICD-10 code for multifocal fibrosclerosis?
The ICD-10-CM code for multifocal fibrosclerosis is M35.5 (sometimes written as M355). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is M35.5 (Other systemic involvement of connective tissue) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report multifocal fibrosclerosis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M35.5 group to?
When multifocal fibrosclerosis 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 M35.5 a CC or MCC?
CMS lists M35.5 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 6 closely related codes in its exclusion list.
What is the ICD-9 equivalent of M35.5?
Under the General Equivalence Mappings, multifocal fibrosclerosis converts to ICD-9-CM 710.8 (diff connect tis dis NEC). The mapping is approximate, so confirm the match fits the documentation.
Does M35.5 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage. M35.5 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).
