ICD-10 Code C43.121 – Malignant melanoma of left upper eyelid, including canthus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C43.121 – Malignant melanoma of left upper eyelid, including canthus
What it is
This code identifies a malignant melanoma arising on the left upper eyelid, including the canthus. Use it when documentation specifies this exact eyelid location and confirms melanoma.
Clinical signs
Findings may include a pigmented or changing eyelid lesion, irregular borders, or local growth on the left upper lid. Clinical features vary; refer to documentation.
When to use this code
Use C43.121 when the record states malignant melanoma of the left upper eyelid, including the inner or outer canthus if documented as part of that site. You should code from provider documentation, pathology, or a clear final diagnosis.
Do not use for
Do not use this code for benign eyelid lesions, non-melanoma skin cancers, or melanoma at a different eyelid site. Check documentation if laterality or exact location is unclear.
Coding tip
Confirm both laterality and the upper-eyelid/canthus location before assigning C43.121.