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ICD-10-CM 2027

ICD-10 code for tendon accessory

Q79.8

Other congenital malformations of musculoskeletal system

✓ Billable / specific

From the official ICD-10-CM alphabetic index entry “Accessory (congenital) › tendon”. Page updated September 29, 2026.

About coding tendon accessory

The ICD-10-CM code for tendon accessory is Q79.8 (Other congenital malformations of musculoskeletal system).

Within Q79, choose Q79.8 (Other congenital malformations of musculoskeletal system) only when documentation doesn't support a more specific option: congenital diaphragmatic hernia (Q79.0), other congenital malformations of diaphragm (Q79.1), Exomphalos (Q79.2), gastroschisis (Q79.3), prune belly syndrome (Q79.4), other congenital malformations of abdominal wall (Q79.5), Ehlers-Danlos syndromes (Q79.6) and congenital malformation of musculoskeletal system, unspecified (Q79.9).

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.

Common questions about tendon accessory ICD-10 codes

What is the ICD-10 code for tendon accessory?

Q79.8 — Other congenital malformations of musculoskeletal system.

Is Q79.8 billable?

Yes. Q79.8 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can Q79.8 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict Q79.8 as a principal diagnosis.

Is Q79.8 a CC or MCC?

No. Q79.8 is neither a CC nor an MCC under MS-DRG v44.0.