This question is regarding what DOS to report for the professional component of a pathology service. Pt had breast/sentinel node biopsies with stains on 8/22/2012. We billed for all services performed that day and were paid. We are pathologists working in the hospital but not employed by the hospital so we bill for only the professional component of the services. This is Medicare. On 9/28/2012, the specimen was retrieved from archives at the request of the treating physician for additional testing. My pathologist performed the ER/PR measures (88360x2w/26 modifier) on the archived specimen and then sent it to outside lab for the HER2-NEU testing. The outside lab performs the test and sends the report back to us for interpretation. We bill the 88367x2 w/ 26 modifier. Should I report the DOS for this 88367 as the date the specimen was archived and sent out to lab or as the date we recieved the report back from the outside lab??