C50.329Malignant neoplasm of lower-inner quadrant of unspecified male breast

C50.329 is the ICD-10-CM diagnosis code for malignant neoplasm of lower-inner quadrant of unspecified male breast. It belongs to category C50 (malignant neoplasm of breast), block C50 (malignant neoplasms of breast) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C50.32, choose C50.329 (unspecified male breast) only when documentation doesn't support a more specific option: right male breast (C50.321) and left male breast (C50.322).

Use an additional code to identify estrogen, and other hormones and factors receptor status (Z17.-).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 582 (Mastectomy for Malignancy with CC/MCC, relative weight 1.8006), DRG 583 (Mastectomy for Malignancy without CC/MCC, relative weight 1.8006), DRG 597 (Malignant Breast Disorders with MCC, relative weight 1.7383), DRG 598 (Malignant Breast Disorders with CC, relative weight 1.0962) and DRG 599 (Malignant Breast Disorders without CC/MCC, relative weight 0.6925), in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It is on the CMS list of diagnoses consistent only with male patients (the sex-conflict edit itself was retired in FY2025).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 175.9 (malignant neoplasm of other and unspecified sites of male breast).