ICD-10 Code C48.1 – Malignant neoplasm of specified parts of peritoneum (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C48.1 – Malignant neoplasm of specified parts of peritoneum
What it is
C48.1 identifies a malignant tumor arising in specified parts of the peritoneum, the thin membrane lining the abdominal cavity. Use it when documentation names a primary or secondary cancer in those peritoneal sites.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include abdominal distension, pain, ascites, or a mass, but the code is assigned from the documented anatomic site and malignant nature, not from symptoms alone.
When to use this code
Use C48.1 when the provider documents malignant neoplasm of a specified peritoneal location and no more specific peritoneal code is given. It may also fit when pathology, imaging, or operative notes clearly identify malignant involvement of those peritoneal parts. Check documentation if the site is described only generally as peritoneal.
Do not use for
Do not use this code for benign peritoneal lesions, inflammation, or nonspecific abdominal malignancy without peritoneal site confirmation. If the record identifies a different abdominal or pelvic primary site, code that diagnosis instead.
Coding tip
Confirm the exact peritoneal subsite in the note; unspecified wording usually requires a different code or further clarification.