Learn about the ICD 10 Coding Guidelines for Breast Mass and how they can help healthcare providers accurately diagnose and treat patients.
Breast lumps or masses can be benign or malignant. To ensure accurate coding, it is important to have a basic understanding of breast anatomy, including the quadrants and clock positions. In this article, we will discuss the Quadrants of the breast and coding guidelines for breast lump or mass, or malignant neoplasms of the breast based on breast quadrants and clock position.
Quadrants of the breast (ICD 10 Coding Guidelines for Breast Mass)
The breast is divided into four quadrants
- Upper outer (superolateral) quadrant
- Upper inner (superomedial) quadrant
- Lower outer (Inferolateral) quadrant
- Lower inner (inferomedial) quadrant
How to Capture Breast Lesion Locations
ICD 10 Coding Guidelines for Breast Mass:- ICD-10-CM groups the diagnosis codes for breast lesions based on the “quadrant” of the breast where the lesions are found. Physicians must report a breast lesion’s location to the highest degree of specificity.

The ICD 10 code should be assigned accurately based on Breast Quadrant & Clock Position when a physician documents the location of a breast lesion using the location on a clock. sometimes physicians describe in the report location of a breast lump, mass, or tumor using a clock position.
Right Breast | Clock position | Left breast |
---|---|---|
Overlapping quadrant | 12 o’clock | Overlapping quadrant |
Upper Inner Quadrant | 1 o’clock | Upper Outer Quadrant |
Upper Inner Quadrant | 2 o’clock | Upper Outer Quadrant |
Overlapping quadrant | 3 o’clock | Overlapping quadrant |
Lower Inner Quadrant | 4 o’clock | Lower Outer Quadrant |
Lower Inner Quadrant | 5 o’clock | Lower Outer Quadrant |
Overlapping quadrant | 6 o’clock | Overlapping quadrant |
Lower Outer Quadrant | 7 o’clock | Lower Inner Quadrant |
Lower Outer Quadrant | 8 o’clock | Lower Inner Quadrant |
Overlapping quadrant | 9 o’clock | Overlapping quadrant |
Upper Outer Quadrant | 10 o’clock | Upper Inner Quadrant |
Upper Outer Quadrant | 11 o’clock | Upper Inner Quadrant |
In ICD-10 CM, the following codes are correlated:
C50 Malignant Neoplasm of Breast
code | Description |
C50.1x | The central portion of the breast |
C50.2x | Upper Inner Quadrant |
C50.3x | Lower Inner Quadrant |
C50.4x | Upper Outer Quadrant |
C50.5x | Lower Outer Quadrant |
C50.8x | Overlapping Quadrant |
N63.1 Unspecified lump in the right breast
code | Description |
N63.10 | Unspecified Quadrant |
N63.11 | Upper Outer Quadrant |
N63.12 | Upper Inner Quadrant |
N63.13 | Lower Outer Quadrant |
N63.14 | Lower Inner Quadrant |
N63.15 | Overlapping Quadrants |
N63.2 Unspecified lump in the left breast
code | Description |
N63.20 | Unspecified Quadrant |
N63.21 | Upper Outer Quadrant |
N63.22 | Upper Inner Quadrant |
N63.23 | Lower Outer Quadrant |
N63.24 | Lower Inner Quadrant |
N63.25 | Overlapping Quadrant |
Examples for assigning ICD 10 code based on Breast Quadrant & Clock Position
1] The physician or healthcare provider may document the location as a lump in the right breast at the 2 o’clock position. Can you suggest the correct code for a lump located at the 2 o’clock position in the right breast?
Answer – N63. 12 for Unspecified lump in the right breast, upper inner quadrant at 2 o’clock position.
2] physician documented a Malignant neoplasm in the Left breast at the 2 o’clock position. Can you suggest the correct code for malignant neoplasm in the Left breast at the 2 o’clock position?
Answer– C50. 412 for Malignant neoplasm of upper-outer quadrant of left female breast
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