Z17.421Hormone receptor negative with human epidermal growth factor receptor 2 negative status

Z17.421 is the ICD-10-CM diagnosis code for hormone receptor negative with human epidermal growth factor receptor 2 negative status. It belongs to category Z17 (estrogen, and other hormones and factors receptor status), block Z17 (estrogen, and other hormones and factors receptor status) and chapter 21 (factors influencing health status and contact with health services). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within Z17.42 (hormone receptor negative), Z17.421 is specifically for hormone receptor negative with human epidermal growth factor receptor 2 negative status. Related codes cover with human epidermal growth factor receptor 2 positive status (Z17.420).

Code first malignant neoplasm, such as: malignant neoplasm of breast (C50.-) and malignant neoplasm of ovary (C56.-).

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 951 (Other Factors Influencing Health Status, relative weight 0.5577), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), 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 not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.

It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.

It was added in FY2025, effective October 1, 2024.