ICD-10 Code C43.12 – Malignant melanoma of left eyelid, including canthus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C43.12 – Malignant melanoma of left eyelid, including canthus
What it is
C43.12 identifies a malignant melanoma arising on the left eyelid, including the inner or outer canthus. Use it when the documentation specifies a primary skin melanoma at this exact eyelid site.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include a new or changing pigmented lesion on the eyelid, irregular borders, color variation, ulceration, or bleeding, with pathology confirming melanoma.
When to use this code
Use this code when the provider documents malignant melanoma of the left eyelid or left canthus, and the lesion is primary to that site. It also applies when pathology or specialist notes confirm the diagnosis and laterality. If the record only says “eyelid melanoma” without side, check documentation.
Do not use for
Do not use C43.12 for benign eyelid lesions, non-melanoma skin cancers, or melanoma on the right eyelid or unspecified eyelid. Check documentation if the lesion is metastatic rather than a primary eyelid melanoma.
Coding tip
Verify laterality and anatomic site carefully; “including canthus” is part of the code description, so do not default to a more general eyelid melanoma code.