For a couple of years, it's been possible to track the progress of a molecular pathology case through the Medicare appeals system, which works through independent review contractors, a federal administrative law judge, a Medicare board of administrative law judges, and eventual the federal courts.
The lab in question can use DNA fingerprinting to confirm that the tissue in a paraffin block is a perfect match to the patient's DNA (based on blood or saliva). Some local MAC decisions had found that this was not a Medicare benefit but a lab quality operations procedure.
This summer, a federal judge agreed with the CMS agency that this type of DNA fingerprinting was not, in itself, a payable Medicare benefit as a laboratory service. The case is online here.
Early parts of the Medicare case, from February 2013, online here, and September 2012, here. A discussion of the case is also available here (page 4 forward) by Wachler, who represented the lab.