ICD-10 Code C44.509 – Unspecified malignant neoplasm of skin of other part of trunk (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C44.509 – Unspecified malignant neoplasm of skin of other part of trunk
What it is
This code identifies a malignant skin tumor on the trunk when the exact site is not specified. Use it when the documentation confirms skin cancer but does not name a more precise trunk location.
Clinical signs
Clinical features vary; refer to documentation. Skin cancers may appear as a new, changing, nonhealing, or irregular lesion, but the record must support malignancy and an unspecified trunk site.
When to use this code
Use C44.509 when the provider documents a malignant neoplasm of the skin on the trunk and does not specify chest, back, abdomen, or another exact subsite. It is appropriate when pathology, biopsy, or assessment confirms malignancy but the chart remains nonspecific. Check documentation if the lesion is described only as suspicious or atypical.
Do not use for
Do not use this code for benign skin lesions, carcinoma in situ, or lesions with a clearly documented, more specific trunk location. Check documentation if the diagnosis is uncertain or if another skin cancer code fits better.
Coding tip
Code the most specific documented site first; use C44.509 only when the trunk location cannot be narrowed further.