ICD-10 Code C21.2 – Malignant neoplasm of cloacogenic zone (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C21.2 – Malignant neoplasm of cloacogenic zone
What it is
C21.2 identifies a malignant tumor arising in the cloacogenic zone, the transitional area near the anorectal junction. Use it when documentation specifies this exact anatomic site.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings may include rectal bleeding, pain, a mass, or altered bowel habits, but you should code only what is documented.
When to use this code
Use C21.2 when the provider documents primary cancer of the cloacogenic zone or transitional zone at the anorectal junction. It also fits pathology, imaging, or operative notes that clearly localize the malignancy to this site.
If the record only says anal canal, rectum, or anorectal cancer without further detail, check documentation before assigning this code. The precise site matters for accurate coding and staging support.
Do not use for
Do not use this code for benign anorectal lesions, dysplasia, or unspecified anal or rectal cancers. Check documentation if the tumor site is described elsewhere or remains unclear.
Coding tip
Code C21.2 only when the cloacogenic zone is explicitly named; otherwise query for the exact primary site.