Q34.1 Congenital cyst of mediastinum

The ICD-10-CM code for Congenital cyst of mediastinum is Q34.1 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

17: Congenital malformations, deformations and chromosomal abnormalities (Q00-QA0)

Section

Q30-Q34: Congenital malformations of the respiratory system (Q30-Q34)

Category Q34

5 codes (4 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Q34.1:

• Cyst (colloid) (mucous) (simple) (retention) › mediastinum, congenital
• Cyst (colloid) (mucous) (simple) (retention) › congenital NEC › mediastinum

U.S. Hospital Utilization

• An estimated 240 U.S. inpatient stays in 2023 included Q34.1 among the documented diagnoses.
• 130 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

POA indicator for congenital conditions/anomalies and Q00-Q99 exception

Congenital conditions and anomalies Assign “Y” for congenital conditions and anomalies except for categories Q00- Q99, Congenital anomalies, which are on the exempt list. Congenital conditions are always considered present on admission.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)