ICD-10-CM > C00-D49 > C50-C50 > C50 > C50.3 > C50.31 C50.31 Malignant neoplasm of lower-inner quadrant of breast, female Non-Billable/Non-Specific Codes C50.311Malignant neoplasm of lower-inner quadrant of right female breastC50.312Malignant neoplasm of lower-inner quadrant of left female breastC50.319Malignant neoplasm of lower-inner quadrant of unspecified female breast