ICD-10 Code C43.9 – Malignant melanoma of skin, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C43.9 – Malignant melanoma of skin, unspecified
What it is
C43.9 identifies a malignant melanoma of the skin when the site is not specified in the record. Use it for a confirmed skin melanoma, but only when documentation does not name the exact anatomic location.
Clinical signs
Clinical features vary; refer to documentation. Melanoma is typically described as an irregular pigmented skin lesion, sometimes changing in size, shape, color, or border, and may be confirmed by pathology.
When to use this code
Use this code when the provider documents malignant melanoma of the skin and does not specify the site, such as trunk, face, or limb. It may also apply when the pathology report confirms melanoma but the chart lacks a precise location. If the site is documented elsewhere, code the more specific melanoma code instead.
Do not use for
Do not use C43.9 for benign moles, dysplastic nevi, or non-melanoma skin cancers. If the lesion site is known, select the specific melanoma code rather than an unspecified code.
Coding tip
Check the pathology and operative notes first; if the anatomic site is missing, use C43.9 only after confirming the diagnosis is malignant melanoma.