Malignant neoplasm of axillary tail of left female breast

This code signifies a primary cancerous tumor originating in the axillary tail (tail of Spence) of the patient's left breast. This specific anatomical location is an extension of the breast tissue into the axilla. The malignancy is confirmed as the initial site of cancer, not a metastasis from another primary tumor.

Apply this code when documentation clearly indicates a primary malignant neoplasm located in the axillary tail of the left breast. This is typically supported by pathology reports confirming malignancy and imaging studies (e.g., mammogram, MRI) localizing the tumor to this specific breast quadrant. Use when the patient is female.

• Ensure the documentation specifies "left" breast and "axillary tail" to differentiate from other breast quadrants or laterality.
• Verify that the neoplasm is explicitly stated as "primary" to avoid confusion with metastatic disease.
• Confirm the patient's sex is female, as there are separate codes for male breast malignancies.