What is the ICD‑10‑CM code for a malignant neoplasm of the upper‑outer quadrant of the right breast in a female patient who is estrogen‑receptor negative?

ICD-10-CM Coding for Malignant Neoplasm of Upper Outer Quadrant of Right Breast, Female, Estrogen Receptor Negative

The ICD-10-CM code for a malignant neoplasm of the upper outer quadrant of the right breast in a female patient who is estrogen receptor negative is C50.411 (malignant neoplasm of upper-outer quadrant of right female breast) combined with Z17.0 (estrogen receptor negative status [ER-]).

Primary Diagnosis Code

• C50.411 is the specific anatomic site code for malignant neoplasm of the upper-outer quadrant of the right female breast 1, 2
• This code follows the ICD-10-CM convention based on the site of the neoplasm in the body, which is the standard approach for cancer coding 3
• The code structure uses the TNM staging system and anatomical information as the foundation for classification 1, 2

Additional Required Code for Receptor Status

• Z17.0 must be added as a secondary code to indicate estrogen receptor negative status 1, 4
• Estrogen receptor (ER) status is a critical predictive factor that determines treatment eligibility and must be documented in the pathological report 1, 2, 5
• ER status should be assessed using immunohistochemistry (IHC) with standardized methodology such as Allred score or H-score 1, 2
• Tumors with <1% ER IHC staining are considered ER-negative 6

Clinical Context for Coding Accuracy

• Pathological confirmation is mandatory before any treatment is initiated, preferably obtained through core needle biopsy with ultrasound or stereotactic guidance 1, 2, 5
• The pathological report should include histological type (most commonly invasive carcinoma of no special type, previously called ductal carcinoma, representing 70-75% of cases), tumor grade, and complete receptor status including ER, progesterone receptor (PR), and HER2 1, 2
• If ER/PR and HER2 are negative on initial biopsy, retesting on the surgical specimen is advisable to account for tumor heterogeneity 1, 5

Important Coding Considerations

• The ICD-10-CM system requires both the anatomic site code and the receptor status code for complete documentation 1, 4
• ER-negative status has significant prognostic and therapeutic implications, as these patients are not candidates for endocrine therapy and typically require chemotherapy-based treatment approaches 7, 8
• Accurate coding is essential for cancer registry data, treatment planning, and epidemiological tracking 9, 10, 3