Neoplasm of uncertain behavior of retroperitoneum

This code signifies a tumor located in the retroperitoneal space whose biological behavior (benign or malignant) cannot be definitively determined from pathological examination. These neoplasms exhibit features that are neither clearly benign nor clearly malignant, requiring further investigation or monitoring.

Apply this code when pathology reports describe a retroperitoneal mass as "of uncertain behavior," "borderline malignancy," or "indeterminate." It is appropriate for initial diagnosis when definitive classification is pending or when the tumor's nature remains ambiguous after all diagnostic workup.

• Ensure documentation explicitly states the retroperitoneal location and the uncertain behavior of the neoplasm.
• Do not use this code if the tumor is definitively diagnosed as benign (D17.7, D20.0, D20.1) or malignant (C48.0, C48.1, C48.2).
• Consider sequencing this code as the primary diagnosis when the uncertain neoplasm is the reason for the encounter, followed by any associated signs or symptoms.