ICD-10 Code C73 – Malignant neoplasm of thyroid gland (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C73 – Malignant neoplasm of thyroid gland
What it is
C73 identifies a malignant tumor arising in the thyroid gland. Use it when documentation states thyroid cancer or malignant neoplasm of thyroid, without a more specific site or histology code.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include a thyroid mass, neck swelling, hoarseness, or enlarged cervical lymph nodes, but diagnosis is usually confirmed by pathology or imaging.
When to use this code
Use C73 when the provider documents primary thyroid malignancy and does not specify a more detailed neoplasm code. It also fits encounters for evaluation, follow-up, or management of confirmed thyroid cancer. Code the documented histology or metastatic sites separately when instructed.
Do not use for
Do not use C73 for benign thyroid nodules, goiter, thyroiditis, or uncertain thyroid masses. If documentation only says “rule out” or “suspected,” check documentation and code the confirmed condition.
Coding tip
Verify whether the record identifies primary thyroid cancer, recurrence, or metastasis, because those details may change code selection.