Breast Lump or Mass ICD-10-CM codes

A palpable breast lump with no established diagnosis is category N63, which was expanded in FY2019 to capture side and quadrant. N63.0 is an unspecified lump in an unspecified breast. Right breast lumps are N63.1- and left breast lumps are N63.2-, with the 5th character giving the quadrant: 0 unspecified quadrant, 1 upper outer, 2 upper inner, 3 lower outer, 4 lower inner, 5 overlapping quadrants. Axillary tail lumps are N63.31 and N63.32 and subareolar lumps are N63.41 and N63.42. A lump in the upper outer quadrant of the left breast is N63.21.

N63 is a working diagnosis. Once imaging or biopsy establishes the cause, the specific code replaces it: D24.1 or D24.2 for a fibroadenoma or other benign neoplasm by side, N60.01 or N60.02 for a solitary cyst, N60.11 or N60.12 for fibrocystic changes, and C50.- for carcinoma. Breast pain without a mass is N64.4 (mastodynia).

Abnormal imaging without a palpable lump is a chapter 18 finding, not N63: R92.0 mammographic microcalcification, R92.1 mammographic calcification, R92.2 inconclusive mammogram, R92.3- dense breasts, R92.8 other abnormal imaging findings. A routine screening mammogram is Z12.31, and family history of breast cancer (Z80.3) or genetic susceptibility (Z15.01) is added when documented.