ICD-10 Code C51.1 – Malignant neoplasm of labium minus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C51.1 – Malignant neoplasm of labium minus
What it is
C51.1 identifies a malignant tumor arising in the labium minus, one of the inner folds of the vulva. Use it when documentation specifies cancer of the minor labium or inner labial tissue.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records may describe a vulvar mass, ulceration, bleeding, pain, itching, or a lesion that appears suspicious on examination and is confirmed as malignant.
When to use this code
Use this code when the provider documents primary cancer of the labium minus, including biopsy-confirmed malignancy or a clearly stated diagnosis. It is appropriate for encounters focused on evaluation, staging, follow-up, or management of this specific site. Check documentation if the note only says vulvar cancer without a precise location.
Do not use for
Do not use C51.1 for malignant neoplasm of other vulvar sites, such as labium majus or overlapping vulvar lesions. Do not assign it when the diagnosis is benign, dysplastic, or unspecified; check documentation.
Coding tip
Verify the exact anatomic site in the pathology or operative note before coding, because vulvar cancers are site-specific.