ICD-10 Code C40.9 – Malignant neoplasm of unspecified bones and articular cartilage of limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C40.9 – Malignant neoplasm of unspecified bones and articular cartilage of limb
What it is
This code identifies a malignant bone or cartilage tumor in a limb when the exact bone or joint cartilage site is not documented. Use it for primary cancers arising in the bones or articular cartilage of an arm or leg.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include localized pain, swelling, a palpable mass, or imaging evidence of a destructive bone lesion in an extremity.
When to use this code
Use C40.9 when the provider documents a malignant neoplasm of bone or articular cartilage in a limb but does not specify the exact anatomic site. It is appropriate when pathology, imaging, or the assessment confirms malignancy and the record remains nonspecific. If laterality or exact bone is documented elsewhere, code that specific site instead.
Do not use for
Do not use this code for benign bone tumors, metastatic disease to bone, or malignancies clearly arising outside the bones or articular cartilage. Check documentation if the lesion is in soft tissue or another primary site.
Coding tip
Assign this code only after confirming the tumor is primary to bone or articular cartilage and the limb site is unspecified.