ICD-10-CM 2027
ICD-10 code for synovium cyst rupture
From the official ICD-10-CM alphabetic index entry “Rupture, ruptured › synovium (cyst)”. Page updated September 29, 2026.
About coding synovium cyst rupture
The ICD-10-CM code for synovium cyst rupture is M66.10 (Rupture of synovium, unspecified joint). The official index lists 13 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on M66.10.
Within M66.1, choose M66.10 (unspecified joint) only when documentation doesn't support a more specific option: shoulder (M66.11), elbow (M66.12), wrist (M66.13), hand and fingers (M66.14), hip (M66.15), ankle, foot and toes (M66.17) and other site (M66.18).
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 557 (Tendonitis, Myositis and Bursitis with MCC, relative weight 1.489) and DRG 558 (Tendonitis, Myositis and Bursitis without MCC, relative weight 0.8875), 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.
More specific synovium cyst rupture codes (official index)
- ankle M66.17 — Rupture of synovium, ankle, foot and toes
- elbow M66.12 — Rupture of synovium, elbow
- finger M66.14 — Rupture of synovium, hand and fingers
- foot M66.17 — Rupture of synovium, ankle, foot and toes
- forearm M66.13 — Rupture of synovium, wrist
- hand M66.14 — Rupture of synovium, hand and fingers
- pelvic region M66.15 — Rupture of synovium, hip
- shoulder region M66.11 — Rupture of synovium, shoulder
- specified site NEC M66.18 — Rupture of synovium, other site
- thigh M66.15 — Rupture of synovium, hip
- toe M66.17 — Rupture of synovium, ankle, foot and toes
- upper arm M66.12 — Rupture of synovium, elbow
- wrist M66.13 — Rupture of synovium, wrist
Common questions about synovium cyst rupture ICD-10 codes
What is the ICD-10 code for synovium cyst rupture?
- M66.10 — Rupture of synovium, unspecified joint. More specific codes apply when the documentation supports them: M66.17, M66.12, M66.14, M66.17 and others below.
What is the ICD-10 code for ankle synovium cyst rupture?
- M66.17 — Rupture of synovium, ankle, foot and toes (header code; choose a more specific subcode).
What is the ICD-10 code for elbow synovium cyst rupture?
- M66.12 — Rupture of synovium, elbow (header code; choose a more specific subcode).
What is the ICD-10 code for finger synovium cyst rupture?
- M66.14 — Rupture of synovium, hand and fingers (header code; choose a more specific subcode).
What is the ICD-10 code for foot synovium cyst rupture?
- M66.17 — Rupture of synovium, ankle, foot and toes (header code; choose a more specific subcode).
What is the ICD-10 code for forearm synovium cyst rupture?
- M66.13 — Rupture of synovium, wrist (header code; choose a more specific subcode).
What is the ICD-10 code for hand synovium cyst rupture?
- M66.14 — Rupture of synovium, hand and fingers (header code; choose a more specific subcode).
Is M66.10 billable?
- Yes. M66.10 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can M66.10 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict M66.10 as a principal diagnosis.
Is M66.10 a CC or MCC?
- No. M66.10 is neither a CC nor an MCC under MS-DRG v44.0.