Carcinoma in situ of vulva

This code represents the presence of abnormal, pre-invasive cancerous cells confined to the epithelial layer of the vulva, without evidence of invasion into deeper tissues. It signifies a high-grade lesion that, if left untreated, has the potential to progress to invasive squamous cell carcinoma.

Assign this code when pathology reports confirm carcinoma in situ of the vulva, often identified as vulvar intraepithelial neoplasia III (VIN III) or severe dysplasia. This diagnosis typically follows a biopsy performed due to abnormal findings on a colposcopy or visual inspection.

• Do not code with N90.1 (moderate dysplasia of vulva or VIN II) as these are distinct diagnoses.
• Ensure the pathology report explicitly states "carcinoma in situ" or "VIN III" for accurate coding.
• Sequence this code as the primary diagnosis when it is the reason for the encounter, such as for treatment planning or excision.