ICD-10 Code C40.30 – Malignant neoplasm of short bones of unspecified lower limb (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C40.30 – Malignant neoplasm of short bones of unspecified lower limb
What it is
C40.30 identifies a malignant neoplasm arising in the short bones of an unspecified lower limb. Use it when the record documents cancer in a foot or other short bone of the lower extremity, but the exact side is not specified.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include localized pain, swelling, or a mass in the affected lower limb bone, with imaging or biopsy supporting malignancy.
When to use this code
Use this code when the provider documents a primary malignant tumor in the short bones of the lower limb and does not specify right or left. It also fits when the site is clearly a short bone, but laterality is unavailable in the note or report. If the lesion is metastatic, secondary, or in a different bone group, check documentation before assigning C40.30.
Do not use for
Do not use C40.30 for benign bone tumors, secondary bone cancer, or malignancies in long bones or unspecified bone sites. If the record names the right or left lower limb, choose the laterality-specific code.
Coding tip
Confirm both the anatomic site and laterality; unspecified lower limb should be used only when the documentation truly lacks side detail.