ICD-10 Code C43.51 – Malignant melanoma of anal skin (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C43.51 – Malignant melanoma of anal skin
What it is
C43.51 identifies a malignant melanoma arising in the skin of the anus. Use it for a primary skin cancer diagnosis documented in the anal skin region.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include a pigmented or changing anal skin lesion, irregular borders, ulceration, bleeding, or pruritus, with diagnosis confirmed by pathology.
When to use this code
Use C43.51 when the provider documents malignant melanoma specifically of the anal skin or anal margin skin. Code it from biopsy or operative pathology when the lesion is clearly described as cutaneous, not mucosal. If the site is unclear, check documentation before assigning the code.
Do not use for
Do not use this code for melanoma of the rectum, anal canal, or other noncutaneous anorectal sites. If the record only states “melanoma of anus” without skin involvement, check documentation.
Coding tip
Confirm the exact anatomic site in the pathology or operative note before coding, because anal skin and anal canal are coded differently.