Radiology Coding Alert

Question: A patient came in for a scheduled diagnostic mammography after she felt a lump in her right breast. The radiologist performed a bilateral diagnostic mammography and noted in their report that the lump is located at the 9 o’clock position of the right breast.

Since 9 o’clock falls on the dividing line between the upper outer and lower outer quadrants, which code should I assign to report the diagnosis?

Massachusetts Subscriber

Answer: This is a tricky diagnosis to report, and luckily, you have multiple options available. One option is to report both quadrants where the lump resides, so in this case, you could assign N63.11 (Unspecified lump in the right breast, upper outer quadrant) and N63.13 (Unspecified lump in the right breast, lower outer quadrant). The other option is to report N63.15 (Unspecified lump in the right breast, overlapping quadrants), which is reserved for conditions where the lump is present in multiple quadrants like the 3, 6, 9, and 12 o’clock positions.

ICD-10-CM code family N63.- (Unspecified lump in breast) requires you to specify the breast quadrant in which the lump resides. However, there isn’t an official guideline in the ICD-10-CM code set to indicate which code or codes to assign in situations like the one you specified.

A transmittal about ICD-10-CM changes to Medicare’s National Coverage Determination (NCD) for mammograms provides guidance for coding overlapping quadrants. According to the NCD, “Dual dx codes depicting specific quadrants can be reported instead of unspecified quadrants if found more appropriate by provider” (www.cms.gov/Regulations-and-Guidance/Guidance/Transmittals/2018downloads/R2202OTN.pdf). With this information, you can assign just N63.15, or you can choose to assign both N63.11 and N63.13 to specify the location of the lump.

Of course, your best approach is to review your individual payer policies to see how the payer would prefer the diagnosis be reported.