ICD-10 Code C77.4 – Secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C77.4 – Secondary and unspecified malignant neoplasm of inguinal and lower limb lymph nodes
What it is
This code identifies metastatic malignant disease involving lymph nodes in the groin or lower limb region. Use it when the cancer is secondary or unspecified and the site is the inguinal or lower-extremity lymph nodes.
Clinical signs
Findings may include enlarged, firm, or fixed inguinal nodes on exam or imaging. Clinical features vary; refer to documentation for the primary cancer and confirmed nodal involvement.
When to use this code
Use C77.4 when the provider documents secondary malignant neoplasm in inguinal or lower-limb lymph nodes, whether from a known primary site or when the metastatic site is specified but the primary is not. It is also appropriate when the record states unspecified malignant neoplasm in these nodes. Code the primary malignancy separately if documented.
Do not use for
Do not use this code for benign lymph node enlargement, infection, or lymphoma. Check documentation if the record describes primary nodal cancer rather than metastasis.
Coding tip
Confirm the exact nodal location and whether the malignancy is secondary before assigning C77.4.