Malignant neoplasm of retroperitoneum

This code signifies the presence of a cancerous tumor originating in the retroperitoneal space. This area is located behind the peritoneum in the abdomen and contains organs such as the kidneys, adrenal glands, and major blood vessels. The malignancy can arise from various tissue types within this region, including connective tissue, fat, or lymphatic tissue.

This code is appropriate when documentation confirms a primary malignant neoplasm located within the retroperitoneum. This diagnosis is typically established through imaging studies (e.g., CT, MRI) and confirmed by biopsy. Use when the pathology report definitively identifies a malignant tumor of retroperitoneal origin.

• Ensure the documentation specifies "malignant" to differentiate from benign retroperitoneal tumors.
• If the primary site is known to be another organ (e.g., kidney, adrenal gland) and has metastasized to the retroperitoneum, code the primary site first, followed by the appropriate secondary malignancy code.
• Distinguish from neoplasms of specific retroperitoneal organs (e.g., kidney, adrenal gland) which have their own specific codes. This code is for malignancies originating within the retroperitoneal space itself, not necessarily from a specific organ within it.