Carcinoma in situ of scalp and skin of neck

This code signifies the presence of non-invasive malignant epithelial cells confined to the epidermis (carcinoma in situ) affecting the skin of the scalp or neck. This represents an early stage of squamous cell carcinoma or basal cell carcinoma where the tumor has not yet invaded the dermis.

Apply this code when pathology reports confirm carcinoma in situ originating from the skin of the scalp or neck. Documentation should clearly state "carcinoma in situ" or "intraepidermal carcinoma" without evidence of invasion. This code is appropriate for lesions such as Bowen's disease when located in these specific anatomical areas.

• Differentiate from invasive squamous cell carcinoma (e.g., 173.4, 173.8) or basal cell carcinoma (e.g., 173.4, 173.8) based on pathology.
• Ensure the documentation specifies "in situ" and the precise anatomical location (scalp or neck).
• Do not use for melanoma in situ; refer to codes within the 230.x series for melanoma.