ICD-10 Code C48.0 – Malignant neoplasm of retroperitoneum (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C48.0 – Malignant neoplasm of retroperitoneum
What it is
C48.0 identifies a malignant tumor arising in the retroperitoneum, the space behind the abdominal lining. Use it when documentation states a primary cancer in that anatomic site.
Clinical signs
Clinical features vary; refer to documentation. Patients may have a deep abdominal or back mass, pain, fullness, or nonspecific pressure effects from a retroperitoneal tumor.
When to use this code
Use C48.0 when the provider documents primary malignant neoplasm of the retroperitoneum, including retroperitoneal sarcoma or other specified malignant growth in that location. Code the site as documented, and confirm whether the tumor is primary, secondary, or unspecified if the record is unclear.
Do not use for
Do not use this code for malignant neoplasms clearly documented in a different abdominal or pelvic organ. Check documentation if the lesion is metastatic, uncertain, or only described as an abdominal mass.
Coding tip
Verify the exact anatomic site and whether the malignancy is primary before assigning C48.0.