Histopathology Coding

We are moving forward in implementing LOINC as the standard for Laboratory Tests and we are under the process of mapping local test codes to LOINC.I would like to know how Histopathology ordering & reporting is mapped to LOINC.

We have two different LIS in our organization.

In System 1, the Histopathology tests are coded based on the tissue/site type. For example ‘Biopsy - Appendix’, ‘Biopsy - Kidney’ etc.

In System 2, there is only one test called ‘Histopathology Examination’ and the requesting clinician has to mention the sites/tissues separately.

We could not get much information from the manual or from internet about coding of Histology tests in LOINC. As we need to mention the tissue/site separately in HL7 message, we feel that the second option is better. Moreover we need to maintain only one code. Please let us know the best way for coding and reporting Histopathology tests. If anyone has any reference material or any implementation reference please forward.

Please advice.