Carcinoma in situ of anal canal

This code describes the presence of malignant cells that are confined to the epithelial layer of the anal canal, without invasion into the underlying stroma. It represents a pre-invasive form of cancer, often referred to as high-grade dysplasia or intraepithelial neoplasia, specific to the anal canal.

Use this code when pathology reports confirm carcinoma in situ of the anal canal. This diagnosis is typically made following biopsy or surgical excision of a suspicious lesion. Documentation should clearly state "carcinoma in situ" or "intraepithelial neoplasia, high-grade" within the anal canal.

• Differentiate from invasive anal canal carcinoma; this code is strictly for non-invasive lesions.
• Ensure documentation specifies "anal canal" as the site; other anal or rectal sites have different codes.
• Review pathology reports carefully for the exact nature and extent of the lesion.