ICD-10 Code D05.91 – Unspecified type of carcinoma in situ of right breast (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D05.91 – Unspecified type of carcinoma in situ of right breast
What it is
This code identifies carcinoma in situ in the right breast when the specific histologic type is not documented. It means abnormal cells are confined to the breast ducts or lobules and have not invaded nearby tissue.
Clinical signs
Clinical features vary; refer to documentation. It is often identified on imaging or biopsy, and the pathology report should confirm in situ disease in the right breast.
When to use this code
Use D05.91 when the record states carcinoma in situ of the right breast but does not specify ductal, lobular, or another type. Apply it after biopsy or pathology confirms in situ disease. If the note later identifies a specific subtype, code that documented condition instead.
Do not use for
Do not use this code for invasive breast cancer or for carcinoma in situ of the left breast. If the documentation names a specific subtype, check documentation and code the more specific diagnosis.
Coding tip
Confirm laterality and whether the pathology report says “in situ” before assigning D05.91.