ICD-10-CM 2027
ICD-10 code for Pseudomyxoma peritonei
Secondary malignant neoplasm of retroperitoneum and peritoneum
From the official ICD-10-CM alphabetic index entry “Pseudomyxoma peritonei”. Page updated September 29, 2026.
About coding Pseudomyxoma peritonei
The ICD-10-CM code for Pseudomyxoma peritonei is C78.6 (Secondary malignant neoplasm of retroperitoneum and peritoneum).
Within C78 (secondary malignant neoplasm of respiratory and digestive organs), C78.6 is specifically for secondary malignant neoplasm of retroperitoneum and peritoneum. Related codes cover lung (C78.0), mediastinum (C78.1), pleura (C78.2), other and unspecified respiratory organs (C78.3), small intestine (C78.4), large intestine and rectum (C78.5), liver and intrahepatic bile duct (C78.7) and other and unspecified digestive organs (C78.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 374 (Digestive Malignancy with MCC, relative weight 2.1109), DRG 375 (Digestive Malignancy with CC, relative weight 1.1838) and DRG 376 (Digestive Malignancy without CC/MCC, relative weight 0.8929), in MDC 06 (Diseases and Disorders of the Digestive 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 Pseudomyxoma peritonei ICD-10 codes
What is the ICD-10 code for Pseudomyxoma peritonei?
- C78.6 — Secondary malignant neoplasm of retroperitoneum and peritoneum.
Is C78.6 billable?
- Yes. C78.6 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can C78.6 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict C78.6 as a principal diagnosis.
Is C78.6 a CC or MCC?
- C78.6 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.