ICD-10-CM 2027
ICD-10 code for lung malformation
From the official ICD-10-CM alphabetic index entry “Malformation (congenital) › lung”. Page updated September 29, 2026.
About coding lung malformation
The ICD-10-CM code for lung malformation is Q33.9 (Congenital malformation of lung, unspecified).
Within Q33, choose Q33.9 (Congenital malformation of lung, unspecified) only when documentation doesn't support a more specific option: congenital cystic lung (Q33.0), accessory lobe of lung (Q33.1), sequestration of lung (Q33.2), agenesis of lung (Q33.3), congenital bronchiectasis (Q33.4), ectopic tissue in lung (Q33.5), congenital hypoplasia and dysplasia of lung (Q33.6) and other congenital malformations of lung (Q33.8).
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 205 (Other Respiratory System Diagnoses with MCC, relative weight 1.8244) and DRG 206 (Other Respiratory System Diagnoses without MCC, relative weight 0.9257), in MDC 04 (Diseases and Disorders of the Respiratory System), 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 lung malformation ICD-10 codes
What is the ICD-10 code for lung malformation?
- Q33.9 — Congenital malformation of lung, unspecified.
Is Q33.9 billable?
- Yes. Q33.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q33.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q33.9 as a principal diagnosis.
Is Q33.9 a CC or MCC?
- No. Q33.9 is neither a CC nor an MCC under MS-DRG v44.0.