ICD-10 Code C40.90 – Malignant neoplasm of unspecified bones and articular cartilage of unspecified limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C40.90 – Malignant neoplasm of unspecified bones and articular cartilage of unspecified limb
What it is
This code identifies a malignant tumor arising in the bones or articular cartilage of an unspecified limb. Use it when the record confirms a primary bone cancer but does not specify the exact bone or whether the arm or leg is involved.
Clinical signs
Typical findings include localized pain, swelling, or a palpable mass in an extremity. Imaging and pathology support the diagnosis; clinical features vary, so refer to documentation when the site details are incomplete.
When to use this code
Use C40.90 when the provider documents a primary malignant neoplasm of bone or articular cartilage in a limb, but the chart does not identify the specific bone or limb. It is appropriate for confirmed cases with incomplete anatomic detail. If laterality or exact site is documented elsewhere, code to that specificity instead.
Do not use for
Do not use this code for metastatic bone disease, benign bone tumors, or malignant neoplasms of soft tissue. Check documentation if the lesion is in a specific bone or if the primary site is actually outside the skeleton.
Coding tip
Look for the exact bone and limb laterality in pathology, imaging, and provider notes before defaulting to unspecified coding.