ICD-10 Code D04.121 – Carcinoma in situ of skin of left upper eyelid, including canthus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D04.121 – Carcinoma in situ of skin of left upper eyelid, including canthus
What it is
This code identifies a noninvasive skin cancer confined to the left upper eyelid, including the canthus. The abnormal cells are present in the skin layer but have not spread into deeper tissue.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include a persistent eyelid lesion, scaling, crusting, or a nonhealing area on the left upper lid or canthus.
When to use this code
Use D04.121 when the provider documents carcinoma in situ specifically on the left upper eyelid, including the canthus. Code it when pathology or clinical assessment confirms a noninvasive malignant lesion limited to that site. If the record only says “eyelid lesion” or the laterality is unclear, check documentation.
Do not use for
Do not use this code for invasive skin cancer, benign eyelid lesions, or unspecified eyelid sites. If the documentation does not confirm carcinoma in situ, check documentation before assigning D04.121.
Coding tip
Verify laterality and exact eyelid location, because ICD-10 distinguishes left upper eyelid, lower eyelid, and canthus separately.