A synovial (bursal) cyst occurring at a site that does not map to any of the more specific laterality-based M71.3x codes — captures cysts at atypical or axial locations such as the lumbar spine, sacrum, or other miscellaneous soft-tissue sites.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 5
- Region
- Other
Documentation tips
What should appear in the chart to support M71.38.
Source · Editorial brief grounded in 5 cited references ↓
- Specify the exact anatomical site in the note (e.g., 'lumbar facet joint synovial cyst at L4-L5') — generic 'bursal cyst' without a site forces the payer to question whether a more specific code exists.
- Distinguish cyst from bursitis: M71.38 is a cyst (fluid-filled sac), not active bursitis. If the note describes inflammation or bursitis, review M71.5x or M70.- instead.
- Document whether the cyst has ruptured — rupture mandates a move to M66.1- (Rupture of synovium) and M71.38 becomes invalid for that encounter.
- For spinal synovial cysts, record the spinal level and laterality (right vs. left facet) to support procedure coding even though M71.38 itself carries no laterality character.
- Note any imaging confirmation (MRI, ultrasound) and cyst size; this supports medical necessity for injection or aspiration and protects against audit clawback.
Related CPT procedures
Procedure codes commonly billed with M71.38. Linking the right diagnosis to the right procedure is what establishes medical necessity.
Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis
Common coding pitfalls
The recurring mistakes coders make with M71.38 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Using M71.38 for knee, hip, shoulder, or ankle/foot bursal cysts — each of those sites has its own laterality-specific child code under M71.3x; M71.38 is only correct when no site-specific code exists.
- Confusing M71.38 with M66.1- (Rupture of synovium): if the provider documents cyst rupture, M71.38 is excluded by Type 1 Excludes and M66.1- must be used.
- Applying M71.38 to overuse or occupational bursitis — those belong to M70.- and are Type 1 Excluded from the entire M71 category.
- Selecting M71.38 for intraspinal extradural cysts without evaluating G96.19 as a potentially more specific alternative when the cyst is clearly meningeal rather than bursal in origin.
- Omitting a secondary code for underlying disease when a 'Code Also' or 'Use Additional' instruction applies at the chapter or section level.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M71.38 is the catch-all code under the M71.3 (Other bursal cyst) subcategory for cyst locations not covered by the site-specific child codes. The M71.3x series assigns dedicated codes to the shoulder (M71.31x), elbow (M71.32x), wrist (M71.33x), hand (M71.34x), hip (M71.35x), knee (M71.36x), and ankle/foot (M71.37x). If the documented site is the lumbar spine, sacrum, thoracic spine, pelvis, or any other location not in that list, M71.38 is correct.
The parent code M71.3 carries an Applicable To note listing 'Synovial cyst NOS,' which means an undifferentiated synovial cyst without a specified anatomical site also routes here. A Type 1 Excludes note bars synovial cyst with rupture (M66.1-) — if rupture is documented, do not use M71.38; code to the M66.1- series instead. Separately, bursitis related to use or overuse belongs to M70.-, and enthesopathies fall under M76-M77; both are excluded from M71 entirely.
For inpatient DRG mapping, M71.38 groups to MS-DRG 557 (Tendonitis, myositis and bursitis with MCC) or 558 (without MCC) under MS-DRG v43.0. AAPC forum discussions confirm M71.38 is a recognized option for intraspinal extradural cysts and synovial facet joint cysts when no more specific code applies, though coders should weigh G96.19 (Disorder of meninges, other) as an alternative for clearly intraspinal presentations.
Sibling codes
Other billable codes under M71.3 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01When should I use M71.38 instead of a more specific M71.3x code?
02Can M71.38 be used for a lumbar facet joint synovial cyst?
03What is the difference between M71.38 and M66.1-?
04Does M71.38 require a laterality character?
05Which DRGs does M71.38 map to for inpatient claims?
06Is M71.38 appropriate for an intraspinal extradural cyst?
07Can M71.38 be used alongside a procedure code for aspiration or injection?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M70-M79/M71-/M71.38
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M71.38
- 04icdlist.comhttps://icdlist.com/icd-10/M71.38
- 05CMS MS-DRG v43.0 Grouper
Mira AI Scribe
Mira AI Scribe captures the anatomical site name, imaging modality and findings (e.g., MRI-confirmed synovial cyst at L4-L5 right facet), cyst size, and any rupture status from the encounter note. Precise site documentation prevents the claim from being downcoded to an unspecified bursal cyst and flags when a more specific M71.3x child code with laterality should be used instead.
See how Mira captures M71.38 documentation