ICD-10-CM 2027 diagnosis code
M85.2Hyperostosis of skull
M85.2 is a valid, billable ICD-10-CM code for hyperostosis of skull. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Looking up by condition? See ICD-10 code for Craniopathy, ICD-10 code for Morel syndrome, ICD-10 code for Buchem's syndrome, ICD-10 code for Morel-Moore syndrome.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About M85.2
M85.2 is the ICD-10-CM diagnosis code for hyperostosis of skull. It belongs to category M85 (other disorders of bone density and structure), block M80-M85 (disorders of bone density and structure) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within M85 (other disorders of bone density and structure), M85.2 is specifically for hyperostosis of skull. Related codes cover fibrous dysplasia (monostotic) (M85.0), skeletal fluorosis (M85.1), Osteitis condensans (M85.3), Solitary bone cyst (M85.4), Aneurysmal bone cyst (M85.5), other cyst of bone (M85.6), other specified disorders of bone density and structure (M85.8) and disorder of bone density and structure, unspecified (M85.9).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 564 (Other Musculoskeletal System and Connective Tissue Diagnoses with MCC, relative weight 1.4908), DRG 565 (Other Musculoskeletal System and Connective Tissue Diagnoses with CC, relative weight 0.9783) and DRG 566 (Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC, relative weight 0.7378), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 733.3 (hyperostosis of skull).
Notes that apply from higher levels
Instructions written at a parent level also apply to M85.2.
Broader instructions also apply from Chapter 13: Diseases of the musculoskeletal system and connective tissue.
Alphabetic index entries
21 entriesTerms in the official ICD-10-CM index that lead to M85.2.
- Buchem's syndrome (hyperostosis corticalis)
- Craniopathy, metabolic
- Disease, diseased › Morgagni's (syndrome) (hyperostosis frontalis interna)
- Disorder (of) › bone › density and structure › hyperostosis of skull
- Hyperostosis (monomelic) › cortical (skull)
- Hyperostosis (monomelic) › frontal, internal of skull
- Hyperostosis (monomelic) › interna frontalis
- Hyperostosis (monomelic) › skull
- Leontiasis › ossium
- Morel (-Stewart)(-Morgagni) syndrome
- Morel-Moore syndrome
- Morgagni's › syndrome
- Morgagni-Stewart-Morel syndrome
- Stewart-Morel syndrome
- Syndrome › Buchem's
- Syndrome › Morel-Moore
- Syndrome › Morel-Morgagni
- Syndrome › Morgagni (-Morel) (-Stewart)
- Syndrome › Stewart-Morel
- Syndrome › van Buchem's
- Van Buchem's syndrome
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 08 · Diseases and Disorders of the Musculoskeletal System and Connective Tissue
ICD-9-CM equivalent
Converter →- 733.3Hyperostosis of skullexact
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about M85.2
Is M85.2 billable?
- Yes. M85.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M85.2 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M85.2 as a principal diagnosis.
Is M85.2 a CC or MCC?
- No. M85.2 is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does M85.2 group to?
- M85.2 is used in the MS-DRG v44.0 logic for MS-DRG 564 (Other Musculoskeletal System and Connective Tissue Diagnoses with MCC), MS-DRG 565 (Other Musculoskeletal System and Connective Tissue Diagnoses with CC) and MS-DRG 566 (Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for M85.2?
- The CMS General Equivalence Mappings map M85.2 to ICD-9-CM 733.3.