ICD-10 Code C40.21 – Malignant neoplasm of long bones of right lower limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C40.21 – Malignant neoplasm of long bones of right lower limb
What it is
C40.21 identifies a malignant tumor arising in the long bones of the right lower limb, such as the femur or tibia. Use it when documentation specifies a primary bone cancer in that anatomic site.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include localized bone pain, swelling, tenderness, or a pathologic fracture, with imaging or pathology supporting a malignant bone lesion.
When to use this code
Use this code when the provider documents a malignant neoplasm in a long bone of the right lower extremity and identifies the site clearly. It is appropriate for primary bone cancer at the femur, tibia, or other long bone on the right side. Check documentation if laterality or bone type is unclear.
Do not use for
Do not use this code for benign bone tumors, metastatic disease to bone, or malignancies in non-long bones. If the record does not specify the right lower limb, verify the laterality before coding.
Coding tip
Match the documented bone and laterality exactly; if the site is vague, query the provider before assigning C40.21.