ICD-10 Code C44.500 – Unspecified malignant neoplasm of anal skin (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C44.500 – Unspecified malignant neoplasm of anal skin
What it is
C44.500 identifies a malignant skin tumor located on the anal skin when the record does not specify the exact histology. Use it for cancer involving the skin at the anal opening, not for internal anal canal disease.
Clinical signs
Findings may include a persistent anal skin lesion, ulceration, bleeding, crusting, or a nonhealing mass. Clinical features vary; refer to documentation, pathology, or biopsy results when available.
When to use this code
Use this code when the provider documents an unspecified malignant neoplasm of the anal skin and the site is clearly the skin rather than the canal. It also fits when the chart confirms malignancy but does not name the cell type. Check documentation if the lesion is described only as perianal or anorectal.
Do not use for
Do not use C44.500 for benign skin lesions, dysplasia, or cancers of the anal canal or rectum. If the documentation names a different primary site or a specific histology, code that diagnosis instead.
Coding tip
Confirm both the anatomic site and the malignant nature of the lesion before assigning C44.500.