MS-DRG · FY 2026 v43.0
MS-DRG 599 – Malignant Breast Disorders without CC/MCC
A Medical DRG in MDC 09 (Diseases & Disorders of the Skin, Subcutaneous Tissue & Breast). Inpatient cases group to DRG 599 when the ICD-10-CM principal diagnosis is one of the 74 codes listed below and no secondary diagnosis on the CC or MCC lists is present. Its FY 2026 relative weight is 0.7332 with a geometric mean length of stay of 2.4 days.
Medical DRG – assigned by principal diagnosis✓ Official CMS v43.0 dataset
0.7332
Relative Weight
2.4
Geometric Mean LOS (days)
2.8
Arithmetic Mean LOS (days)
74
Principal Diagnosis Codes
Severity family
DRG 597with MCCWeight 1.6671 · GMLOS 4.7 daysDRG 598with CCWeight 1.1313 · GMLOS 3.4 daysDRG 599without CC/MCCWeight 0.7332 · GMLOS 2.4 days
How a case is assigned to DRG 599
The grouper first assigns the case to MDC 09 from the principal diagnosis and finds no qualifying operating-room procedure (this is a Medical DRG; ICD-10-PCS codes do not drive assignment here), then applies the severity split from secondary diagnoses: with MCC → 597; with CC → 598; without CC/MCC → 599.
ICD-10-CM
Principal Diagnosis Codes 74 codes · 4 categories
74 of 74 shown
C50 Malignant neoplasm of breast57 codes
- C50.011 Malignant neoplasm of nipple and areola, right female breast
- C50.012 Malignant neoplasm of nipple and areola, left female breast
- C50.019 Malignant neoplasm of nipple and areola, unspecified female breast
- C50.021 Malignant neoplasm of nipple and areola, right male breast
- C50.022 Malignant neoplasm of nipple and areola, left male breast
- C50.029 Malignant neoplasm of nipple and areola, unspecified male breast
- C50.111 Malignant neoplasm of central portion of right female breast
- C50.112 Malignant neoplasm of central portion of left female breast
- C50.119 Malignant neoplasm of central portion of unspecified female breast
- C50.121 Malignant neoplasm of central portion of right male breast
- C50.122 Malignant neoplasm of central portion of left male breast
- C50.129 Malignant neoplasm of central portion of unspecified male breast
- C50.211 Malignant neoplasm of upper-inner quadrant of right female breast
- C50.212 Malignant neoplasm of upper-inner quadrant of left female breast
- C50.219 Malignant neoplasm of upper-inner quadrant of unspecified female breast
- C50.221 Malignant neoplasm of upper-inner quadrant of right male breast
- C50.222 Malignant neoplasm of upper-inner quadrant of left male breast
- C50.229 Malignant neoplasm of upper-inner quadrant of unspecified male breast
- C50.311 Malignant neoplasm of lower-inner quadrant of right female breast
- C50.312 Malignant neoplasm of lower-inner quadrant of left female breast
- C50.319 Malignant neoplasm of lower-inner quadrant of unspecified female breast
- C50.321 Malignant neoplasm of lower-inner quadrant of right male breast
- C50.322 Malignant neoplasm of lower-inner quadrant of left male breast
- C50.329 Malignant neoplasm of lower-inner quadrant of unspecified male breast
- C50.411 Malignant neoplasm of upper-outer quadrant of right female breast
- C50.412 Malignant neoplasm of upper-outer quadrant of left female breast
- C50.419 Malignant neoplasm of upper-outer quadrant of unspecified female breast
- C50.421 Malignant neoplasm of upper-outer quadrant of right male breast
- C50.422 Malignant neoplasm of upper-outer quadrant of left male breast
- C50.429 Malignant neoplasm of upper-outer quadrant of unspecified male breast
- C50.511 Malignant neoplasm of lower-outer quadrant of right female breast
- C50.512 Malignant neoplasm of lower-outer quadrant of left female breast
- C50.519 Malignant neoplasm of lower-outer quadrant of unspecified female breast
- C50.521 Malignant neoplasm of lower-outer quadrant of right male breast
- C50.522 Malignant neoplasm of lower-outer quadrant of left male breast
- C50.529 Malignant neoplasm of lower-outer quadrant of unspecified male breast
- C50.611 Malignant neoplasm of axillary tail of right female breast
- C50.612 Malignant neoplasm of axillary tail of left female breast
- C50.619 Malignant neoplasm of axillary tail of unspecified female breast
- C50.621 Malignant neoplasm of axillary tail of right male breast
- C50.622 Malignant neoplasm of axillary tail of left male breast
- C50.629 Malignant neoplasm of axillary tail of unspecified male breast
- C50.811 Malignant neoplasm of overlapping sites of right female breast
- C50.812 Malignant neoplasm of overlapping sites of left female breast
- C50.819 Malignant neoplasm of overlapping sites of unspecified female breast
- C50.821 Malignant neoplasm of overlapping sites of right male breast
- C50.822 Malignant neoplasm of overlapping sites of left male breast
- C50.829 Malignant neoplasm of overlapping sites of unspecified male breast
- C50.911 Malignant neoplasm of unspecified site of right female breast
- C50.912 Malignant neoplasm of unspecified site of left female breast
- C50.919 Malignant neoplasm of unspecified site of unspecified female breast
- C50.921 Malignant neoplasm of unspecified site of right male breast
- C50.922 Malignant neoplasm of unspecified site of left male breast
- C50.929 Malignant neoplasm of unspecified site of unspecified male breast
- C50.A0 Malignant inflammatory neoplasm of unspecified breast
- C50.A1 Malignant inflammatory neoplasm of right breast
- C50.A2 Malignant inflammatory neoplasm of left breast
C79 Secondary malignant neoplasm of other and unspecified sites2 codes
D05 Carcinoma in situ of breast12 codes
- D05.00 Lobular carcinoma in situ of unspecified breast
- D05.01 Lobular carcinoma in situ of right breast
- D05.02 Lobular carcinoma in situ of left breast
- D05.10 Intraductal carcinoma in situ of unspecified breast
- D05.11 Intraductal carcinoma in situ of right breast
- D05.12 Intraductal carcinoma in situ of left breast
- D05.80 Other specified type of carcinoma in situ of unspecified breast
- D05.81 Other specified type of carcinoma in situ of right breast
- D05.82 Other specified type of carcinoma in situ of left breast
- D05.90 Unspecified type of carcinoma in situ of unspecified breast
- D05.91 Unspecified type of carcinoma in situ of right breast
- D05.92 Unspecified type of carcinoma in situ of left breast
ICD-10-PCS
Procedure Codes
Procedure codes do not drive assignment for this DRG. DRG 599 is a Medical DRG, assigned from the principal diagnosis above.
Frequently Asked Questions
What is MS-DRG 599?
MS-DRG 599 (Malignant Breast Disorders without CC/MCC) is a medical DRG in MDC 09 (Diseases & Disorders of the Skin, Subcutaneous Tissue & Breast). Its FY 2026 relative weight is 0.7332 with a geometric mean length of stay of 2.4 days.
What is the difference between DRG 597, 598, 599?
All 3 share the same base category; the severity of secondary diagnoses separates them: 597 (with MCC), 598 (with CC), 599 (without CC/MCC). A major complication or comorbidity (MCC) places the case in the highest-weighted DRG of the family; a CC in the middle; neither in the lowest.
How many diagnosis codes group to DRG 599?
74 ICD-10-CM principal diagnosis codes group to this DRG, spanning 4 three-character categories.
What is the relative weight of DRG 599?
The FY 2026 relative weight of this DRG is 0.7332, meaning reimbursement of roughly 0.73 times the average Medicare inpatient case. Multiply by a hospital's blended base rate for the approximate payment.
← PreviousDRG 598 – Malignant Breast Disorders with CCNext →DRG 600 – Non-Malignant Breast Disorders with CC/MCC
Source: CMS ICD-10 MS-DRG v43.0 Definitions Manual and the FY 2026 IPPS Final Rule (Table 5), effective October 1, 2025 through September 30, 2026. We publish the DRG assignments as CMS defines them and add the navigation, search, and code links.
