2026 ICD-10-CM Diagnosis Code M85.459Solitary bone cyst, unspecified pelvis

ICD-10-CM Codes›M00–M99›M80-M85›M85

ICD-10-CM M85.459
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M85.459 is a billable ICD-10-CM diagnosis code for solitary bone cyst, unspecified pelvis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 553 through 554. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified bone disease and musculoskeletal deformities.

Code Identity

ICD-10-CM Code
M85.459
Billable Status
Yes — Valid for Submission
Code Describes
Solitary bone cyst, unspecified pelvis
Short Description
Solitary bone cyst, unspecified pelvis
Same as the full description in the CMS dataset.
Parent Code
M85.45
Solitary bone cyst, pelvis

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM80-M85Disorders of bone density and structure
CategoryM85Other disorders of bone density and structure
This CodeM85.459Solitary bone cyst, unspecified pelvis

Clinical ClassificationClinical

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

CCSR MUS028
Other specified bone disease and musculoskeletal deformities
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Bone Diseases

Your bones help you move, give you shape and support your body. They are living tissues that rebuild constantly throughout your life. During childhood and your teens, your body adds new bone faster than it removes old bone. After about age 20, you can lose bone faster than you make bone.

Read the full article at MedlinePlus

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

Convert M85.459 to ICD-9-CMHistory

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

ICD-9-CM
733.21 Solitary bone cyst
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 M85.459Overview

Is M85.459 (Solitary bone cyst, pelvis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report solitary bone cyst, unspecified pelvis on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M85.459 group to?

When solitary bone cyst, unspecified pelvis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 553, 554, with relative weights from 0.8301 to 1.2963 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M85.459?

Under the General Equivalence Mappings, solitary bone cyst, unspecified pelvis converts to ICD-9-CM 733.21 (solitary bone cyst). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.