ICD-10 Code C43.8 – Malignant melanoma of overlapping sites of skin (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C43.8 – Malignant melanoma of overlapping sites of skin
What it is
This code identifies a malignant melanoma arising in skin that spans more than one anatomic site or crosses a site boundary. Use it when the record says the lesion overlaps adjacent skin areas and a more specific site is not documented.
Clinical signs
Melanoma may appear as a changing pigmented lesion, new irregular mole, or a lesion with asymmetry, border irregularity, color variation, or growth. Clinical features vary; refer to documentation.
When to use this code
Use C43.8 when the provider documents malignant melanoma of overlapping skin sites, such as a lesion involving two adjoining cutaneous regions. It is appropriate when the chart does not support a single more specific anatomic site. Check documentation if the site description is unclear.
Do not use for
Do not use this code for melanoma confined to one specific skin site or for non-melanoma skin cancers. If the record describes only a primary site, code that site instead.
Coding tip
Query for exact anatomic extent when the note says “overlapping” but the involved sites are not named.