Malignant neoplasm of long bones of unspecified lower limb

This code signifies a primary cancerous tumor originating in the long bones of a lower extremity when the specific side (left or right) is not documented. These long bones include the femur, tibia, and fibula. It indicates a malignant process, not a benign growth or a secondary metastasis.

Use this code when the medical record clearly states a malignant neoplasm of a long bone in the lower limb, but the laterality (left or right) is not specified. This typically occurs in initial diagnostic reports or when documentation is incomplete regarding the affected side. Ensure the physician's documentation confirms the primary nature of the tumor.

• Do not use this code if the laterality (left or right) is documented; instead, select a more specific code (C40.21 or C40.22).
• Always sequence this code as the primary diagnosis when it represents the reason for the encounter or treatment.
• Confirm that the neoplasm is indeed malignant and primary, not secondary (metastatic), which would require a different code from the C79 category.