ICD-10 Code D03.51 – Melanoma in situ of anal skin (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D03.51 – Melanoma in situ of anal skin
What it is
D03.51 identifies melanoma in situ located on the anal skin. It means abnormal melanocytic cells are confined to the epidermis and have not invaded deeper tissue.
Clinical signs
Clinical features vary; refer to documentation. You may see a pigmented or changing lesion in the anal skin area, with biopsy confirming melanoma in situ.
When to use this code
Use this code when the provider documents melanoma in situ specifically involving the anal skin. It fits pathology-confirmed or clinically documented in situ disease without invasion. If the site is described differently, such as anal canal or perianal region, check documentation before coding.
Do not use for
Do not use D03.51 for invasive melanoma, because this code is limited to in situ disease. Do not assign it when the lesion site is unclear or documented as a different anorectal location.
Coding tip
Confirm both the in situ status and the exact anatomic site in the pathology or provider note before assigning D03.51.