ICD-10 Code D01.3 – Carcinoma in situ of anus and anal canal (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D01.3 – Carcinoma in situ of anus and anal canal
What it is
D01.3 identifies a preinvasive malignant lesion in the anus or anal canal. The abnormal cells are confined to the epithelium and have not yet invaded deeper tissue.
Clinical signs
Clinical features vary; refer to documentation. Diagnosis is usually based on pathology showing carcinoma in situ in the anal region, often after biopsy of a suspicious lesion.
When to use this code
Use D01.3 when the provider documents carcinoma in situ, intraepithelial neoplasia at this site, or an equivalent pathology-confirmed noninvasive lesion of the anus or anal canal. Code it when the record clearly states the lesion is confined to the surface tissue and not invasive.
Do not use for
Do not use this code for invasive anal cancer or for unspecified anal lesions without documentation of carcinoma in situ. Check documentation if the pathology report does not clearly confirm the site or depth.
Coding tip
Match the diagnosis to the pathology wording and confirm the anatomic site before assigning D01.3.