The Wild West World of Digital Pathology Coding

 Many have heard the high level result on AMA CPT digital pathology coding:

1. For several years, PLA committee created 8-10 whole slide imaging codes.
2. Then they stopped. Either:
1. The slides included human reviewing, so PLA was "nix" due to physician work.
2. The slides were H&E, so PLA had "no new biomarker" to work with and refused to code.
3. In February and May 2026, AMA CPT began putting a few WSI codes (including H&E only) into Category III.

There are many nuances.

• Cat III CLFS Yes.  CMS may load the Cat III codes into the CLFS process (crosswalk gapfill) since FDA, CLIA, and CMS previously have categorized WSI as CLFS.  They have done this even under close review as ADLT.
• Cat III CLFS No.  CMS may NOT load the Cat Iii codes,
• Either because they no longer think they are CLFS, or
• Because Cat III codes are "temporary."
• There is little precedent for loading Cat III codes as CLFS, but CLFS tests have not been put into Cat III as may be happening.
• FDA WSI TEST = CODE TOO.  Under PAMA CMS (or AMA) is obligated to make new codes for FDA cleared or approved tests, so any given dig path code (assuming it is  CLFS) should demand a code, whether PLA or Cat III.
• Non destructive.  There is much less moat around glass slide algorithms, as imaging is non distrctive.  This is a huge difference from MAAA RNA tests built on disappearing and scarce FFPE archives from trials.
• Cat III not branded.  While PLA codes are proprietary (either to one lab or to one FDA mgfr), Cat III codse are NOT proprietary as long as another service fits the words of the code.
• CMAA?? Soon we will have a new AMA coding system CMAA and nobody knows the new rules.
• Broadband or Fed Ex?  Can Dig path assays be run on DICOM files are a new glass slide scanned?   
• The literature is confusing.  Some test 6 scanners and all work great on algorithm "X."  Some try 6 scanners and only the original validates the algorithm.  This is a big deal logistically.
• NCCN passed the Artera prostate FDA test.   What's next?  Breast?
• FDA online.  Artera Prostate has an online 24 page FDA review.    The new breast test will have that online in 1-3 months.  https://www.accessdata.fda.gov/cdrh_docs/reviews/DEN240068.pdf
• WSI as "non DOS."  If CMS doesn't class WSI as "a CLIA test" then the whole 14 day rule, DOS rule, doesn't apply and it's easy to unbundle as it is a local service by the generic DOS principal.