Pathology/Lab Coding Alert

Question: A dermatology office sends us a specimen block and asks us to prepare MART-1/Melan A slides. We return the prepared slides and their dermatopathologist reads the slides and assigns a diagnosis based on the entire case. Should we bill 88342-TC, and should we just use a generic code for the diagnosis, such as 709.9, since we don’t have the final diagnosis?

Colorado Subscriber

Answer: Assuming that your lab prepares MART-1/Melan A slides using qualitative immunohistochemistry (IHC) technique, the correct code for the service is 88342 (Immunohistochemistry [including tissue immunoperoxidase], each antibody). Because your lab prepares the slides but does not provide the pathologist’s interpretation service, you are correct to bill with modifier TC (Technical component).

Regarding the diagnosis, you should not select a generic code such as 709.9 (Unspecified disorder of skin and subcutaneous tissue) without documentation to that effect. Because you don’t have the final diagnosis, you should use whatever diagnosis the dermatopathologist assigned as the reason for excision.