ICD-10 Code D09.9 – Carcinoma in situ, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D09.9 – Carcinoma in situ, unspecified
What it is
D09.9 identifies carcinoma in situ when the site is not specified in the record. It means abnormal cells are confined to the epithelium and have not invaded deeper tissue.
Clinical signs
Clinical features vary; refer to documentation. Diagnosis is usually based on pathology showing in situ disease, with no evidence of invasion or metastatic spread.
When to use this code
Use D09.9 when the provider documents carcinoma in situ but does not name the anatomic site. This code is also appropriate when the record confirms in situ disease and the location remains unspecified after review. You should not infer a site from context.
Do not use for
Do not use this code for invasive malignant neoplasms, dysplasia, or benign lesions. If the documentation identifies a specific site, code the more precise carcinoma in situ code instead.
Coding tip
Query for the exact anatomic site whenever the note says only “carcinoma in situ.”